The objective of this research was; to study best practice in small school management under the Office of the Basic Education Commission, to explore the small school development model, and to study the results of the using the small school development model by using professional learning community in mathematics and sciences subjects. The research was divided into 3 phases: Step 1: Study the best practices in small school management. The sample were a small school with O-NET test higher than the national average O-NET test in academic year 2018. Step 2: Finding the small school development model by focus group were organized between education administrators, school administrators and teachers. And Step 3: Study on the effects of small school development model by using professional learning community. The samples were 3 small schools which O-NET test in mathematics and sciences subjects below the national average O-NET test. The data were analyzed by mean, standard deviation, t-test, and content analysis.