Abstract: Compared with other mechanical oil production model,the obvious characteristics of screw pump are higher system efficiency.According to the energy loss of every part of screw pump well,established system efficiency analysis model for the well.Applied this model to Erlian oil field shows that the main factors to effect system efficiency of Erlian screw pump well are small pumping parameters,mismatch of supplying and producing and excessive electric motor configuration.For this,proposed corresponding measurements to effectively and accurately improve system efficiency of screw pump wells,it is also useful for other oil field.