Our work proposes universal rules for simplifying the numerical design of phase metasurface, which alleviates the problem of lots of iterative calculations and low design efficiency due to the consideration of dispersion and phase distribution of materials and so on. According to the different effects of structure sizes and materials on metasurface, the parameters can be divided into two categories: one affects the 2π phase shifting mechanism and phase linearity, and the other affects the anomalous deflection performance of the device, such as bandwidth, reflection, and angle of emergence. Through the proposed design rules, the uncertain parameters can be reduced by more than 60%, greatly improving the numerical design efficiency. To verify the rules, we design several metasurfaces: the large angle deflector at 430 to 630 nm waveband and the broadband (more than 700 nm) high-efficiency reflective metasurface in the near-infrared, where the perfect 2π phase linearity is achieved at the communication wavelength 1550 nm. Moreover, we simply combine two trapezoids in one unit, so that the metasurface can be used as a beam splitter to verify the generality of the rules. The optimal conversion efficiency of equal power beam splitter is more than 95%, and the reflectivity is more than 0.85 at near-infrared. It is of guiding significance to the theoretical design of phase metasurface with excellent performance.