PT reverse charge incident always happens in power system due to incorrect operation or equipment failure. This paper analyzes the working principle of traditional PT parallel device, summarizes its deficiency in anti reverse charge, and develops an anti reverse charge device with programmable controller as core for PT parallel. The analog (voltage) criterion is increased to its parallel conditions. It does not allow to parallel when in-phase voltage difference is greater than the set value. At the same time, a self recovery circuit with new electronic device (PPTC) is designed in the parallel circuit, in order to block circuit when the parallel loop current is too large, then the circuit can automatically split. And when the failure is lift, the parallel loop circuit can renew to conduct. The developed device can fundamentally prevent reverse charge in parallel operation, thus it can prevent the air switch to trip and the equipment to be damaged, which ensures the safety and stability operation of the power grid.