Oral test is always one of teacher selection methods. There are not only individual testing in oral test, but also collective oral test and leaderless group discussion and etc. This study employed collective oral test as a performance assessment of classroom management. Firstly, this study designed the rating scale and observational score. These contents divided into three dimensions including of appearance, wording, and ability and insight. We modified Flanders Interaction Analysis System to take score as a method of analyzing collective oral testing. Secondly, there is statistically significant difference between with interviewers A and B by using traditional rating method, that the correlation coefficient is .472. There is statistical significance between interviewers A by using traditional rating method and B by using modified FIAS rating method, that the correlation coefficient is .510. There is statistical significance between with interviewers B by using traditional rating method and B by using modified FIAS rating method, that the correlation coefficient is .819. The result of this study has two benefits. One benefit is easy to understand the performance of collective oral testing for candidate. The other benefit is to reduce the halo effect by interviewer.