The utility model provides a device and system for uninterruptible replacement of an electric energy meter. In the utility model, a wire inlet voltage transformer outputs wire inlet voltage; a wire outlet voltage transformer outputs wire outlet voltage; the wire inlet voltage and the wire outlet voltage are respectively inputted to a polarity comparison module; the polarity comparison module compares polarities of the wire inlet voltage and the wire outlet voltage; and if the polarities are inconsistent, an alarm is given out by use of an alarm module. Furthermore, in the utility model, a current transformer is used for outputting a wire inlet current, and the wire inlet current and the wire outlet voltage are inputted into an electric energy calculation module so that the electric energy can be calculated. When the polarities are consistent, a wire outlet circuit breaker and an isolation disconnecting link are disconnected, the assembly and disassembly of the electric energy meter can be conducted, and after the electric energy meter is switched off, the device can calculate the electric energy in the assembly and disassembly. According to the utility model, the uninterruptible replacement of the electric energy meter can be achieved, uninterrupted electricity is fundamentally ensured during the replacement, the reliability rate of the power supply is improved, the electric energy during the assembly and disassembly can also be calculated, and thus no loss will be brought to a power company.