The invention discloses a multi-power-supply automatic transfer switch (ATS) signal processing system based on multiple processors and a control method for the multi-power-supply ATS signal processing system. The system comprises a first processor, a second processor, a third processor, a plurality of three-phase voltage signal acquisition modules, a plurality of circuit breaker position signal acquisition modules, a plurality of modules for acquiring phase differences between any two phases of power supplies, a plurality of power supply phase-A voltage frequency signal acquisition modules and a display. By virtue of the multi-power-supply ATS signal processing system and the control method, a transient voltage and current acquisition function can be realized, and due to a processing architecture with the multiple processors, the signal processing system can simultaneously process massive data and finish work under a complicated control system. Furthermore, the three processors are used for implementing modularized processing, so that the real-time processing capacity and the data sampling and analysis capacity of the whole system can be improved, and the system can be applied to a complicated multi-power-supply ATS control system.