the performance of multi-antenna spectrum sensing over Nakagami fading channel is analyzed when the received signals from multiple antennas are uncorrelated. Firstly, maximal ratio combining, equal-gain combining and selection combining are employed to combine multiple signals, and then the noise-normalized energy algorithm is adopted to detect the combined signal. And then, detection probability, false alarm probability and average detection probability are derived. Finally, the correctness of theoretical results is verified through the simulation. Meanwhile, the effects of some parameters on the spectrum sensing performance are also simulated and analyzed. These parameters mainly include combining ways, number of antennas and channel fading.