After entering high school, freshmen hope to have rich interpersonal relationships and friendly, warm and harmonious interpersonal relationships. However, after several months of collective life, some students have harmonious interpersonal relationships and are full of energy, while others have bad interpersonal relationships and are very depressed, which has affected their study and life. From psychological counseling and daily life of freshmen, it is not difficult to find that the reasons leading to poor interpersonal relationship are: some students lack a correct understanding of interpersonal communication, some students have personality problems, and some students lack experience and skills in interpersonal communication. High school students' bad cognition of interpersonal communication can be divided into two categories. One is to take others as the center and care too much about whether others are satisfied and happy; One is self-centered, everything is based on personal interests and hostile to others. These two kinds of bad cognition will lead to communication difficulties, and the specific psychological activities are as follows: taking others as the center: I must establish close relationship with everyone around me; If a person is not good to me, it means that there is something wrong with my interpersonal relationship; I should always think about whether others are interested in associating with me; When you accept others' help, you must give it back immediately. Egocentricity: everyone is selfish and untrustworthy; Some people are selfish and unable to associate with them; If you know more, you will lose. People are nice to me because they want to take advantage of me. Personality factors are very important in high school students' interpersonal communication. Bad personality traits or personality defects are easy to give the other person a bad evaluation, resulting in unpleasant feelings and insecurity, thus affecting interpersonal communication. Common personality defects include selfishness, hypocrisy, disrespect, revenge, jealousy, doubt, demanding others, excessive inferiority, complacency, loneliness and stubbornness. These personality defects seriously affect the communication between classmates. Therefore, it is very important for high school students to constantly improve their personality. For high school students, the lack of interpersonal skills is also one of the reasons that affect interpersonal communication. Some students have realized in their daily life that they often want to care about others and don't know where to start; Want to praise others but don't know where to start; Trying to coordinate interpersonal relationships is more complicated; I want to be nice to others, but I can't control my impulse and my language is blunt. Interpersonal communication ability is the synthesis of a person's knowledge, personality, cultivation and various psychological abilities, which reflects a person's comprehensive quality. High school students should pay attention to the cultivation and improvement of their comprehensive quality while cultivating and improving their interpersonal skills. This paper analyzes the common problems and main reasons in interpersonal communication of freshmen in senior high school, aiming at enhancing their mental health and establishing harmonious interpersonal relationships. So how do freshmen build good interpersonal relationships? The following principles can be followed: First, the principle of equality means mutual respect. Seeking respect is a human need. The purpose of communication between students is to accomplish the learning tasks in senior high school together, which stipulates that they are equal in personality, help each other in their studies, and actively understand and care for their classmates. Suhomlinski once pointed out that don't hurt the most sensitive thing in others' hearts-self-esteem. Second, the principle of compatibility is manifested in the understanding, care and love of classmates. Conflicts often occur in interpersonal communication, some because of different levels of understanding, some because of different personalities and tempers, and some because of bad habits and hobbies, which will cause certain misunderstandings between each other. If both sides can treat others with tolerance, many conflicts can be avoided. Third, the principle of mutual benefit The ancients said: "Give it a peach and give it a plum." The principle of mutual benefit requires us to understand each other's values, care and help him more, and keep each other's gains greater than losses, so as to maintain and develop good relations with others. Fourth, the principle of credit Credit means that a person is honest, does not deceive the other party, keeps his promise, and thus gains the trust of others. In interpersonal communication, there is a sense of security in dealing with trustworthy people, and anxiety and doubt in dealing with untrustworthy people. For every adult and student who is determined to become a successful person, keeping promises will add luster to your image.