Fuel injector is a kind of precision device with high machining accuracy, which requires large dynamic flow range, strong anti clogging and anti pollution ability and good atomization performance. The injector receives the injection pulse signal from ECU and controls the fuel injection quantity accurately. The fuel injector characteristics of injector include atomization size, oil mist distribution, oil beam direction, range and diffusion cone angle. These characteristics should meet the requirements of diesel engine combustion system, in order to make mixture formation and combustion perfect, and obtain higher power and thermal efficiency.