Hydrostatic guideway has been widely used for ultra-precision machine tools due to its high stiffness and motion accuracy. In order to optimize the stiffness and motion accuracy of hydrostatic guideway, the effect of different diameters orifice restrictors on the stiffness and deformation of hydrostatic guideway is investigated in detail in this paper. The theoretically optimal structural coefficient is verified through the experiments. Hydrostatic guideway can obtain the maximum stiffness when the value of optimal structural coefficient is 0.707. And changing the diameter of orifice restrictors is an effective method to adjusting the structural coefficient. Due to the error caused by manufacture and assembly of hydrostatic guideway, the optimal structural coefficient is hard to be obtained accurately. Based on this condition, a larger structural coefficient is adopted to reduce the oil pressure in the pocket of hydrostatic guideway effectively, so that the deformation of guideway can be reduced. And finally, the stiffness loss caused by the deformation decreased. In addition, the experimental results show that the maximum deformation of hydrostatic guideway can be reduced from 2.06μm to 1.82μm and the stiffness arise from 1453N/μm to 1855N/μm when orifice restrictors with 0.15mm diameter are used rather than 0.2mm diameter.