Abstract: Based on the energy flow and physical phenomena in the circuit, power theory accurately describes the power characteristics through mathematical expressions and is of great significance in terms of electric energy measurement, harmonics and reactive power compensation. With the widespread application of power electronic technology, non-sinusoidal and asymmetry problems in modern power systems are more serious. But the definition of traditional reactive power is only meaningful for sinusoidal circuits, and lacks theoretical support for reactive power compensation strategy under non-sinusoidal conditions. Based on the geometric algebra approach, we proposed the power multivector theory to solve such problems, which includes active power, scattered power, Budeanu’s reactive power, distortion reactive power and unbalanced power between phases. This approach is suitable for both non-sinusoidal single-phase circuits and three-phase circuits. It can describe the power components well and follows the basic theorem in the circuit. Finally, the power under different working conditions was calculated and simulated to verify this theory. The results show that the power components after division can be accurately measured, and the physical meaning is clear.