Abstract: The subsea christmas tree and well jumper are connected by special subsea connectors and collet connector is commonly used.The connector installed underwater will induce continuous heat transferring to ambient cold seawater and cause excessive temperature drop under shutdown condition.Relevant temperature distribution and heat transfer problems must be evaluated so as to further increase the flow security of the subsea christmas tree.Based on the requirment of subsea hydrocarbon development,a coupled fluid-solid numerical method was adopted to analyze the heat transfer and fluid flow of the collet connector without thermal insulation treatment.In addition,this paper completed the numerical study on heat transfer of the collet connector covered by an insulation cavity(doghouse)and the inner flow field simulation of the collet connector based on the consideration of variable properties of fluids.The results show that local supercooled spot would be present in the connector without any insulation measures and the doghouse could greatly improve the effect of thermal preservation on collet connectors which satisfy the basic principle of eight hours’ thermal insulation for subsea christmas trees.The method of coupling heat transfer of subsea collet connector is feasible in theory and reliable in calculation results.