Questionnaire, also known as questionnaire or inquiry form, is a printed document that systematically records the contents of the investigation in the form of questions. Questionnaires can be forms, cards or bookkeeping. Designing a questionnaire is the key to inquiry and investigation. A perfect questionnaire must have two functions, that is, it can convey the questions to the interviewee and make the interviewee happy to answer them. In order to realize these two functions, certain principles and procedures should be followed when designing the questionnaire, such as time order and category order. Answers can be divided into questionnaire answers, open answers and closed answers.