Abstract: The article instructs the work principle of the injector device and the applyment in the reverse-circulation sampling bit.Then use the FLUNET fluid engineer emulator software to simulate the onerous formed inside of the injector hole when the obliquity is 30,45 and 60 degree.The pressure distributing nephogram and the corresponding numerical value has been gotten.A injector with 3 degrees according the conclusion from FLUENT was designed to experiment in the laboratory.Compare the two values we found that they are anastomose essentially.It shows that using emulator technology to design optimizely is credible and simple,and the cost is lowered,the design cycle is shorten compared with the method through experience and test.