A integral rotary Stirling XD-2A cooler with cooling capacity of 0.4 W is taken as an example to introduce some malfunction encountered in the practical use,after it coupled to focal plane detector Dewar assemblies.Based on failure mechanism analysis,it can benefit the users to easily find out the solution or control methods while investigating any malfunction cause related by the cooler,controller and focal plane detector Dewar assemblies.The malfunction,mechanism analysis and solution or control methods described in this paper are also applicable to other types of integral rotary Stirling cryocooler.