Increasing efforts are being directed towards applying the technologies of micro-fluidic, to the development of micro-devices for a wide range of applications such as medical, biological, engineering and related technologies. The present studies are interested with the design of micro-screw pump for viscous fluid and its operating behaviour, the steady performance of the micro-pump will be investigated numerically. The present numerical investigation is a comparative study of a steady flow behavior in a micro-channel with rotating screw with different operation and design parameters. The numerical investigation is performed using computational fluid dynamic techniques. The FLUENT program as CFD simulation program in the ANSYS 14.0 package used to simulate the pump model. The results of the simulation problem give an agreement with literature experimental results which validate the simulation model that encourage future simulation of the studied system. Theoretical analysis is carried out to study the influence of the helix angle, diameter of the screw, screw length and the thread height (flight depth) to evaluate the optimal dimensions for the pump to obtain the maximum flow rate and pump performance. the effect of screw angular velocity and pump load were studied.