The invention discloses a power model-based power type differential protection algorithm. The method comprises the steps of acquiring the voltage and current sampling data of a to-be-protected element; according to adjusted synchronous sampling data, calculating the instantaneous power sampling value data of all circuit breakers; reducing the instantaneous power sampling value data of all the circuit breakers to the same voltage grade side; respectively calculating the power differential action power and the power differential braking power according to the instantaneous power sampling value data of all the circuit breakers; and conducting the judgment on the power differential protection action region. According to the invention, the actual problems of the current type differential protection algorithm, such as the unbalanced current, the excitation surge current and the surge current identification caused by the gear adjustment of a transformer, the more complex DC converter transformer differential algorithm, the difficult construction of wide-area current differential protection in an AC-DC hybrid power grid and the like, can be solved.