In the multi-antenna signal detection scenarios, there will be both the noise uncertainty and the correlation between the signal samples. Therefore, the performance of traditional multi-antenna energy detection algorithm is poor. A blind signal detection algorithm based on equal gain combination of multi- antenna signals is proposed. The algorithm utilizes the technology of multi-antenna signal combination to compensate the differences among the signals received by different antennas, and then conduct the equal gain combination. The ratios between the combined signal and the single antenna signal are taken as the detection statistical values. The detection threshold and detection probability are derived by using statistical theory. Simulation results show that the proposed algorithm obtains better detection performance than the existing blind signal detection algorithm.