VirtualMud is a software for performing computations of hydraulic in an oil well drilling operations self-developed by COSL which includes Prediction of Temperature, Bit Optimization, Well Strengthening, Wellbore Hydraulic, Torque&Drag, etc. It can accurately calculate the of ECD, ESD and Hole Cleaning Efficiency and the results of the calculation can indicate the risk that the drilling fluid engineer may encounter in the field operation and provide data support for the control measures.