According to flexibility of pneumatic conveying systems with respect to other types of transmission systems, this system has wide application in industry and agriculture processes. One important application of this system is in the loading and unloading tankers and powdery bulk materials such as trucks carrying cement, plaster and sand. Conveying efficiency is associated with pressure, which increases the pressure drop in the pipe, operational efficiency will be reduced. This work presents a computational fluid dynamics (CFD) calculation to predict and evaluate the influence of the pipes type and the inlet mass flow rate on the pressure drop and velocity fields during pneumatic conveying of wheat. The numerical solutions were carried out using spreadsheet and commercial CFD code Ansys Fluent 14.5. The CFD simulations predict excellently the pressure drop and velocity field under different pipe types and inlet mass flow rate. Pressure drop were estimated to be 2780, 3120, and 3360 pa for mass flow rates of 4.33, 5.77 and 8.66 kg/s respectively in Steel pipes. Also there were 2940, 3240 and 3390 for polyethylene pipe that showed the maximum pressure drop in polyethylene pipes is higher than the steel pipes.