The populations were local administrators of Sub-district Administrative Organization (SAO) of Maha Sarakham Province in fiscal year of 2021. The Simple Random Sampling technique was conducted with 400 local administrators. The questionnaire used an instrument for data collection. Multiple Regression Analysis is an inferential statistic for data analysis. Descriptive statistics were mean, and standard deviation. The objective of research was to predict the environmental law knowledge influencing to environmental policy formulation. The finding showed that the prediction equation of relationship between independent variables of Environmental Damage (X1), Natural Resource Damage (X2), Ecological Damage (X3), Civil Liability (X4), Criminal Liability (X5), and Administrative Liability (X6) affecting to Environmental Policy Formulation (Y) of local administrators. It can be explained that Criminal Liability (X5) was the most effect to Environmental Policy Formulation (Y) with 41.20 percent with statistical significance at level of 0.01. However, the other factors also assist to support effective environmental policy formulation of local administrators. To formulate environmental policy, the local administrators need to have actual knowledge and clear understanding in all aspects of environmental law such as environmental damage, natural resource damage, ecological damage, civil liability, criminal liability, and administrative liability, thus they can formulate the effective environmental policy for SAO.