The invention relates to the technical field of power detection tools, in particular to a combined type secondary nuclear phase device of a transformer, reasonable in structure, convenient in use and accurate in display. The combined type secondary nuclear phase device is characterized by being provided with a host, a detection circuit, a detection wire harness and a display output mechanism, a controller and a power supply are arranged in the host, the controller is connected with the power supply, the controller is connected with the detection circuit and the display output mechanism respectively, a STC12C5A60S2 single-chip microcomputer, a triode and an optical coupler which are connected are arranged in the detection circuit, the detection circuit is connected with the STC12C5A60S2 single-chip microcomputer via an A/D (alternating-current) conversion circuit, and an LED color digital screen is arranged in the display output mechanism. Compared with the prior art, the combined type secondary nuclear phase device has the advantages that secondary nuclear phase efficiency can be effectively improved and is reliable in operation, reasonable in structure, convenient in use and the like.