study the teaching learning activity management to reinforce the 12 Thai main core values according to the policy of the National Council for Peace and Order of Secondary Schools under Secondary Educational Service Office Area 6 Samut Prakarn Province. The research instrument was a questionnaire asking about the teaching learning activity management to reinforce the 12 Thai main core values according to the policy of the National Council for Peace and Order. Data were collected from 320 teachers of secondary schools under Secondary Educational Service Office Area 6 Samut Prakarn Province by simple random sampling method. Statistics for data analysis were frequency percentage mean standard deviation and mean difference were tested by ANOVA statistics. The research results revealed that : 1. The management of teaching learning activity to reinforce the 12 Thai main core values of Secondary Schools Samut Prakarn Province classified by status as a whole revealed that the administrators rating was at moderate level and teachers rating was at moderate level ; classified by school sizes as a whole small schools medium schools large schools and extra-large schools rating were at moderate level. 2. The Comparisons of teaching learning activity management to reinforce the 12 Thai main core values of Secondary Schools Samut Prakarn Province classified by school sizes revealed that as a whole of all aspects were not different which was not in agreement with the hypothesis.