Existing OpenMP cost models does not give enough thought to the implementation details of OpenMP programs so they cannot be applied widely to different types of parallel loops. To solve this problem, this study extends the cost model in the most advanced product-level optimizing compiler Open64. Targeting single candidate parallel loop, it establishes a cost model suite for the OpenMP benefit analysis. Besides improving the original DOALL-loop faced cost model in the Open64 compiler, two additional models which are also designed for DOACROSS and DSWP (Decoupled Software Pipelining) loops respectively. The experimental results show that the proposed cost model suite can simulate the execution cost of parallel programs very well, and therefore can better support cost evaluation of OpenMP parallelization.