This is a high pressure capillary viscometer to measure the viscosity of non Newtonian fluids such as drilling mud. I used Solidworks and Ansys to design this viscometer, Constructed it and did the related tests for several fluids. Finding and Doing a practical project was my concern during the study and both my B.S. thesis and M.S. thesis projects were useful and practical. This one was done because of the request of an oil company from Tehran University.