Abstract: Split heat pipes were applied into CAP1400 spent fuel pool (SFP) as a complete passive cooling system, and the evaporation ends of split heat pipes were arranged around SFP. Numerical simulation method was used to analyze the temperature and velocity characteristics of SFP, and natural convection heat transfer ability outside of each row of the evaporation ends was also analyzed. The results show that when active cooling system out of work, this complete passive cooling system can successfully remove the decay heat from SFP and prevent SFP from boiling. The inner evaporation pipes have much higher heat transfer ability and can reach 1.05 times that of the outer pipes. The natural convection heat transfer coefficient is much larger on the upper and lower part than that on the middle part. This work will provide some references for applying split heat pipes into spent fuel pool.