The triangular plate has widely application in the manipulation of the pr angular plate will often have error. In the former solutions, it is very hard to find one kind of simple and common way to solve the equation of deflection curve of the triangular plate. Under uniform load function, this paper uses the reciprocal theorem method to discuss the bending question of triangular plate with the unfixed hypotenuse and fixed side as well as the other side with simple supported, and the unfixed hypotenuse as well as two fixed sides. Thus the method has overcome complicated calculating process appeared in the classical theory, solved the limitations with difficulties to certain questions and established new way to solved the bending question of triangular plate. In the process of calculating, it will take specific proportion, applying the mixed variables method, carrying the calculation on the Matlab platform, and comparing it with the ANSYS finite element analysis result, to prove the result is correct. Thus the paper gives the equation of deflection curve and the graphs which can be employed in the actual project application. Therefore, the paper has certain theoretical value and project significance.