The invention provides a voice coding rate method to affirm the multi-rate voice coder and an affirming voice coding rate in wireless communication system. According to the method, it includes steps as following: the voice signal is coded into voice frame at a voice coding rate; the adjusting information of said voice information coding rate is generated based on the generating ratio or the timesof the received said voice frame in every quality type. The method of the invention adjusts the voice coder mode according to the quality of received voice frame, so the error introduced by estimating the type of channel can be avoided; the accuracy of choice is increased, at the same time the cost of hardware is decreased. Besides, the threshold triggering mode shortens the responding time of the channel change; it suits to track the wireless circumstance which is declined.