Automatic weather station is a professional measuring instrument, the power supply requirements are relatively special. The general power sypply products in the market have relatively simple functions, and can not meet the needs of supporting. Comprehensive analysis of the power requirements of automatic weather station has been made, using the high frequency switching power supply technology. Design and optimization method of current sampling loop in high power condition have been proposed. The output voltage ripple is limitted below 300 mW. Using the DC/DC transform and the current measurement technology of precision and lightning protection technology, the current sampling and logic control circuit have been irgeniously designed. The current voltage measurement, battery charge and discharge protection and lightning protection function have been achieved. The test results show that the power supply is stable in the full range power range, and the performance indexes meet the requirements of automatic weather stations.