The light scintillating caused by atmospheric turbulence,absorption and scattering has a serious impact on the efficiency of the space laser communication system.They can cause the energy attenuation of the laser beam and the decrease of the signal-to-noise ratio(SNR).Detector array diversity reception technology can overcome this effect effectively.Three combining modes of diversity reception with detector array are studied,they are Selection Combining,Equal Gain Combining and Maximal Ratio Combining respectively.The performances of three combining modes are compared at power gain improving and signal to noise ratio.Under the condition of the same atmospheric turbulence and outage probability,Maximal Ratio Combining is the most obvious at improving signals,followed by Equal Gain Combining,and the minimum signal improvement is the Selection Combining.For two detectors diversity reception,SNR improvement factor increases 100% for Maximal Ratio Combining,78.5% for Equal Gain Combining and 50% for Selection Combining compared with the traditional method.Maximal Ratio Combining is complex to achieve and Selection Combining is relatively easy to implement.So the suitable combining method could be selected according to the actual project performance requirements.