Abstract: This paper presents a new method to calculate the limit load of rectangular plate based on the Twin Shear Unified Strength Theory (M.H.Yu,1991). Unified solutions which consist of a series of solutions from the upper load limit based on Twin Shear Yield criterion (M.H.Yu,1961) to the lower load limit based on Tresca Yield criterion are obtained and solution based on Tresca Yield Criterion is a special case of the unified solutions. Influence of weighted parameter b on the limit load of rectangular plate is also proposed, which can be used to fit different properties of different materials. Using this new method to calculate the limit load of concrete rectangular plate, a satisfactory solution is gained.