As a critical component for pool-type Sodium cooled Fast Reactor (SFR), the main vessel plays a major role in holding the entire sodium in the pool. While the Reactor Vessel Cooling System (RVCS) would contribute to the cooling of the main vessel. This paper develops a one-dimensional code and the numerical analysis has been conducted to evaluate the thermal-hydraulic characteristics for RVCS for China Experimental sodium-cooled Fast Reactor (CEFR). Firstly, the code is applied to the analysis on the steady characteristics of RVCS and the results are compared with the design value. The simulation results show that the main vessel is cooled effectively and the comparison results are in good agreement with the design value. Then, in order to study the transient characteristics of RVCS, the code is coupled with the Transient Thermal-Hydraulic Analysis Code for Sodium-cooled fast reactors (THACS). The simulation finds that a reverse flow in RVCS shows up and RVCS could take the decay heat out effectively, which contributes a lot to the core cooling. The code evaluated the thermal-hydraulic characteristics as well as the decay heat removal capacity of RVCS. The results are very promising but further experimental data is still needed to validate the code.