A systematic study of the packer rubber contact pressure under a fixed-displacement load is conducted to gain further insight into the packer seal mechanism. A Y221-114 double rubber packer is investigated using the finite element software ANSYS, where a design of experiments method is utilized to study the effects of the friction coefficient. The results show that the friction coefficient of the packer and the tubing had the greatest effect on contact pressure than other factors. Decreasing the rubber friction coefficient is conducive to forming the double rubber seal and increasing the maximum contact pressure working range. However, there is additionally a slight decrease in the value of maximum contact pressure. The results of the study provide valuable insight into the importance of packer design optimization.