Aiming at the problem of spectrum sensing in cognitive radio under low signal to noise ratio (SNR) and channel fading, proposed a spectrum sensing method based on Stochastic Resonance (SR) and multi-antenna. The received signal of each antenna will pass through SR, to enhance the source signal using noise energy. Then the output of multi-antenna will be combined by Equal Gain Combining (EGC), and Differential Energy Detection (DED_SR) and Periodogram Energy Detection (PED_SR) will be adopted. Simulation experiments compare the traditional Energy Detection (ED), DED_SR and PED_SR. The results show that the detection probability of PED_SR and DED_SR perform higher than ED, but the sensing time also perform higher.