This paper analyzes the calculation results of the existing power factor under the condition of three-phase severe unbalance, and points out the shortcomings of the existing calculation methods in reflecting the actual line utilization. Based on the principle of line power loss equivalence, a new power factor and apparent power calculation method that can accurately reflect the actual line utilization rate is proposed. The upgrade scheme of the existing smart electricity meter to realize the effective power factor and apparent power measurement is given, and the high-accuracy smart electricity meter is used as the test platform to carry out the comparative test with the existing power factor under the condition of three-phase non-sinusoidal unbalance test. The data analysis shows that, compared with the existing power factor and apparent power, the proposed power factor and apparent power can faithfully reflect the actual line utilization rate, which can provide a reasonable basis for the improvement of power factor.