The invention relates to the technical field of transformer station equipment check, and discloses a spare automatic switching logic test method for checking a main transformer mutual switching mode. The method comprises the following steps of: establishing an experimental initial state: regulating analog circuit breaker modules 1DL to 4DL to closed positions; pushing experiment switches AN1 to AN4 to conduction positions; in a test state, pushing the experiment switch 'AN3' to a disconnection position, and operating analog mutual inductor modules 3PT and 4PT without alternating current; operating a detected spare automatic switching device, and disconnecting the analog circuit breaker modules 1DL and 2DL; connecting the analog circuit breaker modules 3DL and 4DL; operating the analog mutual inductor modules 3PT and 4PT to generate three-phase alternating current; and if the detected spare automatic switching logic function is accurate and accords with the requirement, adding the function for operating. The method can conveniently test the protected constant value of the spare automatic switching protection device, is convenient to operate and reliable in results. The method can realize the check operation of the spare automatic switching device of a bridge connection line in a power system, greatly provides test flexibility, and improves the production efficiency.