In the paper,a circuit is proposed which is applied to the FPGA projects with multiple functional modules,so that multiple functional modules can share the bidirectional pins of FPGA.By allowing users to switch the bidirectional pins of the FPGA occupied by the functional module in real-time without obtaining the original code of the FPGA project,the application flexibility of the FPGA project after solidification is improved.By reducing the number of bidirectional pins used in FPGA,the bottleneck of the number of pins in VLSI verification applications is solved.The simulation results show that the theoretical switching delay of the circuit is up to 1 system clock.Applying this circuit to an FPGA project with 4 functional modules,the bidirectional pin occupancy rate of the FPGA can be reduced up to 75%.It’s deduced that the pin occupancy reduction range in FPGA projects containing 2~8 functional modules can reach up to 50%~87.5%.