The objective of this survey research were to study the effect of new entrance examination on mathayomsuksa VI students preparation and teachers instruction of schools under the department of education changwat sakon nakon. The samples were 381 mathayomsuksa VI students and 125 teachers. The sample size of students was calculated by Yamane method. Students were selected by multi-stage random sampling. Teachers were selected by purposive sampling. The research instruments employed in the study were the students questionnaire and the teachers questionnaire that constructed by the researcher. The reliability of the questionnaire was 0.92, and 0.97. The data was analyzed by using SPSS program to calculate the percentage, the mean, and the standard deviation. The results were as follow: 1. The attitude to the effect of new system of university entrance examination on the students preparation.1.1 Using the student grade point average in higher secondary level as a part of the university entrance recruitment. The most effect was the students stress cause they had to use their scores for application to universities, both the university quota and the central entrance examination.1.2 Twice examination in one academic year. The most effect was the students got advantage in the examination scores could be used for both the university quota and the central entrance examination.1.3 Using the best scores for the recruitment. The most effect was the students had a chance to improve themselves for the entrance examination preparation.1.4 Keeping the last three years scores, and the students know their scores before choosing the field of study. The most effect was the students can improve their weak points in the last examination.1.5 Students preparation for the entrance examination. The most effect was the students preparation by revision the past examination tests in questions and topics as the clue to the next examination. 2. Students attitude to the most appropriate of the new system of university entrance examination was they can choose their best scores for the recruitment. 3. The attitude to the effect of new system of university entrance examination on the teachers instruction.3.1 Using the student grade point average in higher secondary level as a part of the university entrance recruitment. The most effect was made the students recognized the process of teaching and learning in the classroom.3.2 Twice examination in one academic year. The most effect was the students got advantage in the examination scores could be used for both the university quota and the central entrance examination.3.3 Using the best scores for the recruitment. The most effect was the students had more chance to enter the university.3.4 Keeping the last three years scores, and the students know their scores before choosing the field of study. The most effect was the students can improve their weak points in the last examination.3.5 Teachers instruction. The most effect was the teachers have got to encouraged students to learn and to motive them for their knowledge. 4. Teachers attitude to the most appropriate of the new system of university entrance examination was the students can choose their best scores for the recruitment.