The Stirling cryocooler component of infrared focal plane array detector used in military investigation requires low mechanical noise.In order to reduce the mechanical noise of the integral Stirling cryocooler,the causes of noise are studied.Results show that the unreasonable design of the compression spring and improper bearing assembly process are the main causes for the mechanical noise of the integral Stirling cryocooler.The adverse effects of the cryocooler in practical application caused by the mechanical noise can be reduced by optimizing the design and assembly process,the performance index of the mechanical noise of the integral Stirling cryocooler meets the application requirements of users.