Thai educational reform under the situation of dynamic change focuses on life long education of the learners through effective education management process together with appropriate technology usage. Improvement of educational standard requires the school administrators’ skills in leading the schools towards sustainable prosperity. The purposes of this research were to study and compare the school administrators’ administration skill under the Secondary Education Service Area Office 17 classified by working experience and size of the schools. The sample used in this research was a group of 320 teachers under the Secondary Education Service Area Office 17. The sample size was calculated using Krejcie and Morgan’s comparison table and proportionate stratified random sampling method. The research instrument was a five-level rating scale questionnaire with a reliability of 0.95. The statistics used for data analysis were: percentage, mean, standard deviation, T-test, One-way ANOVA and Scheffe’s paired difference test