The hydrostatic guide stiffness is one of the key indicators to measure the performance of the guide. The hydrostatic guide with fixed liquid resistance were used as the research object, and the mathematical equations for the hydrostatic guide stiffness, oil film displacement ratio, and initial liquid resistance ratio were derived through theoretical derivation. The results show that with the increase of the initial liquid resistance ratio, the guide shows a distinct stiffness peak, the peak increases with the increase of the initial liquid resistance ratio, and moves to the right. As the stiffness peak increases, the bearing capacity of the guide decreases, and the system overflow loss increases. A method for determining the optimal initial liquid resistance ratio based on the stiffness of the guide under loading conditions is proposed, which provides a basis for improving the overall performance of the hydrostatic guide.