The calculating method of the first O rder Markov model 's parameters in Wireless fading channel is deducted. By the way of which, we study the effects of the parameters of the Physical Layer on the performances of Go-Back-N Protocol. It 's shown that more larger the correlation between adjacent packets gets, more larger the throughput of RLP is. And for Go-Back-N Protocol, when the fading margin of the channel is small, the effect of the number of repeating transmission on the throughput efficient is trivial; when the fading margin become larger, the changing of the throughput efficiency is not obvious. Meanwhile, when the fading margin gets larger, the left frame error rate provided to upper layer is reduced, and the throughput of the protocol even get larger; while when the greatest admissible retransmission value gets larger, the error rates provided to the TCP layer get small, concurrently the performance of the protocol itself is destroyed.