Abstract: The on-site programming of smart energy meters needs to meet the requirement that the main circuit voltage reaches 78% or above. Therefore, when there is no voltage in the main circuit, it is impossible to achieve on-site programming of the energy meter or start dismantling old meters to read the meter's bottom reading. In this regard, some technical personnel will connect the voltage to other circuits on site, start the energy meter to complete programming, which can easily cause personal or equipment safety accidents. To this end, a portable power recovery device has been developed that can output AC power between 50、100、220 V, with overcurrent and overvoltage safety protection functions, improving on-site operation safety and work efficiency.