In this paper, we present the performance analysis of multi-antenna system over Nakagami-n fading channel in wireless communication. Here, firstly we have analyzed the system performance such as probability density function (PDF), and outage probability single antenna system and after then SIMO system over Nakagami-n fading channel. Nakagami-n fading channel is a very popular channel which has its basis on its experimental or mathematical observation. To improve the system performance of the channel and also increase the received SNR (signal to noise ratio), We are using multiple numbers of antennas (using diversity techniques such as selection combining (SC)) at the receiver. In this paper, we have derived the closed form expression for PDF of SNR, and outage probability over Nakagami-n fading channel.