The article introduced the work principle of the injector device and the application in the reverse-circulation sampling drilling bit. Then use the FLUNET fluid engineer emulator software to simulate the onerous formed inside the different obliquity and hole diameter respectively. The pressure distributing nephogram and the corresponding numerical value has been gotten. Injectors with different degrees and different hole diameters according the conclusion from FLUENT be designed to experiment in the laboratory. Comparing the two values we found that they are anastomose essentially. It shows that using emulator technology to design is credible and simple, and the cost is lowered, the design cycle is shorten compared with the method through experience and test.