Domestic undergraduate and graduate students are on the same starting line. Even domestic graduate students should start from American graduate students if they don't apply for a Ph.D. in the United States. The reason is that the United States does not recognize China's graduate education. If they don't think the applicant has reached a certain level, it's still no good.
The advantage of graduate students over undergraduates in the application process is actually scientific research experience, that is, the situation of projects, papers and patents. If graduate students don't have decent papers published (such as SCI, EI, etc. ), there is no essential difference between them and undergraduates except their age in application.
Conditions for applying for a doctorate at California Institute of Technology
All majors in California Institute of Technology have set minimum score requirements such as TOEFL, IELTS, GRE and GPA. According to IELTS official website, the IELTS score of Caltech should be 7.0, and the TOEFL score should not be lower than 90. There is no minimum GPA requirement in the college, but the GPA of most students is above 3.5, and the class ranks in the top 5% or above 10%.