Abstract: CTF (Coolant Boiling in Rod Arrays-Two Fluid) is a new sub-channel thermal/hydraulic simulation code developed by CASL (The Consortium for Advanced Simulation of Light Water Reactors) and PSU (Pennsylvania State University). It can solve steady or transient-state problems efficiently for both single assembly and full-core reactor. Thus, this code solves the computational efficiency and memory consumption problems effectively. First, CTF computes the BEAVRS benchmark in parallel with the domain decomposition technology. The power data which CTF uses are calculated by RMC(a Monte Carlo code for reactor core analysis). After calculating for 268 s, we get detailed fuel pin temperature, water temp and density output results. Accordingly, the efficiency and reliability of CTF is verified. On this basic work of CTF calculation for BEAVRS benchmark,the coupling between RMC and CTS for full-core problem will achieved soon.