Type Ⅱ InAs/GaSb superlattices have the characteristics of adjustable band gap,high quantum efficiency,low dark current,easy fabrication for large array,etc,so it is the main material for the third generation infrared detectors. Type Ⅱ InAs/GaSb superlattices was grown by MBE on GaSb substrate,and the defects of material surface were classified and its causes were analyzed. The influences of growth temperature,growth rate of GaSb,As/In ratio on defects were studied. Through the optimization of growth conditions,high quality type Ⅱ InAs/GaSb superlattices were obtained,which has a certain reference for the fabrication of high quality large format type Ⅱ InAs/GaSb superlattices infrared detectors.