The regenerator is the core component of the Stirling cryocooler, which has a decisive influence on the performance of the Stirling cryocooler. The heat loss of the Stirling cryocooler (including finite heat transfer loss, pressure drop loss and empty volume loss, etc.) is analyzed theoretically, and the effect of increasing the number of meshes and different filling modes on the regenerator performance is also studied experimentally. The experimental results show that increasing the number of meshes can effectively improve the performance of cryocooler, and the mixed arrangement with 400 meshes at the cold end and a small amount of 100 meshes at the hot end has the best effect, which provides a basis for the performance optimization of Stirling cryocooler.