The change from interpretation to just-in-time compilation has improved the performance of Java dramatically. However, further amelioration is still possible. In this paper, a hybrid concurrent compilation and execution model (HCCEM) is proposed, which possesses the potential to surpass JIT by overlapping the production of native code with program execution through multithreaded control. The design of JAFFE, a Java virtual machine based on HCCEM, and some critical problems are also discussed in the implementation such as mode switch,exception handling and hierarchicl multithreads.The experimental result shows that HCCEM can improve the execution speed of java programs efficiently.