This invention relates to a detecting network multicast performance method. The invention mainly includes: firstly, at the test starting point, construct and send the multicast performance measurement request packet with the identification information; then, at each node receiving the said multicast performance measurement request packet, respectively send the performance measurement response packet with the said identification information to the test starting point; finally, in the scheduled time, the test starting point receives the said performance measurement response packet, and according to the identification information, measure the multicast performance parameters. The invention makes small change to the OAM frame format defined in Y.17ethoam, and in the realization of the invention, the process in the sending point and the receiving point is rather simple, and based on the original unicast performance measurement calculation method, it processes the calculation method of multicast performance measurement. Therefore, the invention can be nice to achieve P2MP multicast performance parameter measurement in the Ethernet OAM, thereby assisting OAM to provide a more comprehensive network performance assessment.