Nowadays, students' evaluation of teaching is usually used to assess teaching quality in class based on taking students as center in university. The effect of assessment indicators and setup of system in students' evaluation of teaching on the results of course evaluation is researched continuously in Beijing University of Technology (BJUT). The influence of optimization of the assessment indicators in students' evaluation of teaching on the results of students' evaluation is researched in this paper. The results indicated that the results in students' evaluation of teaching have tendency to be reasonable and follow normal distribution according to optimization of assessment indicators and restriction of excellent rate in students' evaluation of teaching system. Besides, students can rationally analyze and assess teaching effect of courses which they study after considering teaching quality of all courses in whole semester, and present definitely main problem of teaching.