0.01 mm。Controlling the volumetric shrinkage of injection parts effectively is the key step of ensuring high forming precision for drip-emitters, and the injection molding determines directly the volumetric shrinkage. Adopting an orthogonal experimental design method, and by using injection simulations instead of practical experiments, the effects of some important process parameters, such as holding pressure, fill time, holding pressure time etc. on the volumetric shrinkage of emitters in LDPE were studied. The optimum process parameters and the influence degree of process parameters on the average volumetric shrinkage and the volumetric shrinkage variation were obtained. On the basis of the injection simulations, the work of molding trial was succeeded at one time, and the precision of the emitter channel was lower than ±0.01 mm.