The experimental viscosity measurement of a certain type of the solid propellant slurry is carried out by using the press bar-fall ball viscometer. Moreover, the CFD simulation is performed through the ANSYS Fluent software to numerically investigate the press bar-fall ball viscometer. The viscosity-time characteristics of the slurry are studied in detail. The present study shows that, when the steel ball falls in the static slurry, the ball is initially accelerated so that its velocity increases. On the other hand, when the ball velocity reaches a certain value, called the terminal velocity, forces are balanced and the velocity remains constant. The medium viscosity is experimentally measured in the present study. Then proper corrective correlations are applied to the Stokes equation to calculate the medium viscosity according to the simulation results. Comparisons show that results of the numerical simulation are in good agreement with the ones from the experiment. It is observed that the viscosity of the slurry rises exponentially with time, due to the curing reaction. Furthermore, since the shear stress of the dropping ball in the solution is small, the shear rate of the solution during the falling of the ball is very low. Therefore, it is concluded that the falling ball method is capable to accurately determine the static viscosity of the slurry.