The present study proposes a method to optimize the stiffness of structures with the constraint of even reaction forces under static and dynamic loading. The variance of the reaction forces at the Dirichlet boundary are introduced to evaluate the uniformity of the static and dynamic reaction forces. Several formulations for optimal topology design are provided by introducing the constraints of variance of reaction forces. Sensitivity analysis is derived based on the adjoint variable method and verified by the Finite Differentiation Approximation (FDA). Several numerical examples prove the effectiveness of the proposed method.