Speculative Multithreading (SpMT) is an effective mechanism for parallelizing irregular programs which are hard by conventional approaches. SpMT technology can be applied to exploit Thread-Level Parallelism effectively through allowing multiple threads executed in the presence of ambiguous data and control dependences while the correctness of the programs maintained by hardware support. This paper focuses on the thread partitioning method for Prophet, a SpMT compiler system. The thread partitioning method is based on the weighted control flow graph (WCFG) of the procedure. A structural analysis and some heuristic rules are used to partition the WCFG into sub-graphs and each sub-graph represents a candidate thread. The inter-thread data dependences are predicted by pre-computation slice to reduce RAW violation. The thread partitioning method proposed in this paper deals with both loop region and non-loop region partitioning for the consideration of general purpose programs partitioning. Experimental results show that an average speedup of 30% can be achieved by our thread partitioning method.