The present invention discloses a method of call trace on a next generation network (NGN) media gateway (MG). According to the present invention, a softswitch device adds an extended trace indication to an H.248 message related to the call to be traced; the MG determines whether the received H.248 message needs to be traced according to the extended trace indication; and if the H.248 message needs to be traced, trace the call to which the transaction in the H.248 message belongs. By the method, the MG can trace the entire calling process of a call.