In general,high power fiber laser adopts the traditional cooling methods such as water cooling and air cooling,which often cannot meet the actual needs,and thus the laser cannot meet some special applications.Based on the characteristics of phase change materials,the heat treatment of all-fiber laser was analyzed and studied by phase change refrigeration method.The continuous fiber laser output with a working wavelength of 1080 nm and a maximum output power of 409 W is realized.The light to light conversion efficiency is 80 %,which effectively reduces the volume and weight.It provides a reflection for the thermal management of phase change refrigeration for some high optical power fiber lasers.