The flow regime in screw centrifugal pump was simulated by the method of computational fluid dynamics (CFD), which can acquire the distribution of the pressure and relative velocity on the work side and back side of blade. The Rothalpy value along the streamlines of blade was used as a quantitative index of energy loss. The energy loss within the impeller field was analyzed from the perspective of energy loss when the transmission medium is pure water and solid liquid two phase flow, in which the concentration of sand is 20% and the diameter of sand is 0.076mm. The result shows that the front of impeller is a transition region of energy conversion, the screw part is the main region of energy increase, and the friction loss at the middle of screw part has an effect on the working capacity of screw part. Compared with pure water transmission medium, the working capacity of the impeller shows some improvement when the transmission medium is the solid liquid two phase flow. And the energy of the two kind transmission media tends to become average at the outlet of impeller.