A Reynolds equation is presented for the hydrodynamic pressure components between the two faces of a partially or fully laser surface textured mechanical seal (LST-MS) by considering the hydrostatic and hydrodynamic characteristics and cavitation within the sealing fluid film. Galerkin’s method is used to set up the finite element model for the Reynolds equation. The effects of geometric parameters of the spherical dimple on seal performance of a LST-MS are studied. The texturing parameters are numerically optimized to obtain the maximum opening force and/or the maximum ratio of fluid film stiffness to leakage rate. It is shown that a full LST-MS has stronger hydrodynamic effect and lower frictional torque between the two faces than that of a partial LST-MS, but the latter works at a less leakage and a more stable working state. Thus a partial LST-MS is recommended for practical application for its better comprehensive seal performance.