The invention discloses an environment sensing system and method based on a coordinated USV group. The environment sensing system comprises single-vessel sensing modules, a coordinated control system, wireless communication modules, GPS / IMU modules and single-vessel control modules. Each single-vessel sensing module comprises a camera and a laser radar, the laser radar obtains position and motion information of an object, and the camera identifies the object. The coordinated control system comprises a coordinated control unit and a coordinated sensing unit, the coordinated control unit carries out a coordinated control algorithm to command motion of the USV group, and the coordinated sensing unit coordinates states of the single-vessel sensing modules. The wireless communication modules upload state information and environment sensing information of vessels to the coordinated control system, and also transmits instructions of the coordinated control system. Each GPS / IMU module obtains position and attitude information of the corresponding vessel, and assists in normal operation of other systems. The environment sensing system is reasonable in design, high in system hierarchy, and is easy to realize in the aspects of hardware and software.