Abstract: The operational vector diagram of electric energy metering devices serves as a core technical tool for evaluating their operational status. Traditional methods require on-site live-line detection of the phase angle between voltage and current in electricity meters, followed by vector diagram generation based on phase relationships. These approaches suffer from complex workflows, safety risks, and limitations to instantaneous measurements only. To address these issues, this paper proposes an off-site generation method for smart electricity meter vector diagrams, which fully leverages the measurement functions of the meter’s built-in metrology chip. By remotely acquiring 15-minute frozen data (voltage, current, active/reactive power, power factor, etc.) via infrared handheld terminals or electricity information collection systems, combined with coordinated calculations of active/reactive power phase angles and logical criteria based on reactive power metrology principles, this method achieves precise vector diagram generation. Engineering validation demonstrates that the generated vector diagrams exhibit a phase error of≤±1°compared to on-site live-line detection results, eliminating the need for field operations. This approach not only provides reliable data support for automated anomaly diagnosis of metering devices and related large-scale model training, overcoming the traditional limitation of capturing only instantaneous values, but also delivers testing accuracy and performance comparable to, or exceeding, conventional methods under specific conditions. It offers a safer, more efficient, and accurate solution for monitoring and condition assessment of electric energy metering devices, holding significant engineering application value.