Summary of the problem: I am using the Windows 10 32-bit Professional Edition system, and the computer is installed with ISE14.4. When I use the simulator ISIM that comes with this ISE to simulate, the simulator always reports ERROR:Simulator:861 – Failed to link the design. I checked the Verilog code many times and confirmed that there is no error, but the simulation is still the same problem, so I googled it and found that as long as the system is Windows 8 or later, this problem will occur, but I still don't know how to solve it. Finally, I found a solution on a foreign electronic engineering forum. Although I don't know what the principle of solving the problem is, I tried it and the method is indeed effective. In order to prevent the problem from being encountered again in the future, the solution will be recorded. Solution: Find "installation directory\Xilinx\14.x\ISE_DS\ISE\gnu\MinGW\5.0.0\nt\libexec\gcc\mingw32\3.4.2\collect2.exe" and delete it, re-run the emulator, the problem has been solved! !