As most research focuses on improving the acquisition sensitivity and speed in AWGN (Additive White Gaussion Noise) channel,this paper will present the theoretical analysis of acquisition performance for GNSS signal over frequency non‐selective fading channel.The complementary cumulative distribution function for the correlation peak value higher than a threshold Rthis derived when the channel is slow and fast fading respectively.For the Rician fading,when the threshold Rth is larger than a special value,the acquisition performance over slow fading channel will surpass the performance over fast fading channel.Conversely,the performance for fast fading will be better.But,both of them are inferior to the performance over AWGN channel.For the Rayleigh channel,theoretical analysis shows that the acquisition performance for GNSS signal over slow fading channel exceeds the performance over fast fading channel.Finally,the acquisition for GPS signal transmitted over frequency non‐selective fading channel has been simulated and the simulation results confirm the validity of the derivations and analysis.