The invention relates to a synchronous data acquisition method and system for master-slave wireless sensors. The invention belongs to the field of equipment fault state monitoring, wherein the main sensor is responsible for sending a synchronizing signal; the auxiliary processor of the slave sensor is responsible for communicating with the main sensor and the main processor of the auxiliary sensor; when a synchronization signal is received through a physical layer of an auxiliary processor of each slave sensor, the physical layer analyzes a frame header of the synchronization signal and sendsan interrupt signal to a main processor according to the frame header, and each main processor starts synchronous acquisition according to the received interrupt signal. Relative to the prior art, synchronization signals sent to the slave sensor by the master sensor do not need to be transmitted to an application layer by a physical layer, but interrupt signals are directly sent out after the signals are processed by the physical layer, so that each master processor starts synchronous acquisition, the random accumulative error is very small, the time synchronization of data acquisition starting of each master processor can be ensured, and the synchronization precision is improved.