This paper implements the controlled Lagrangian method on nonlinear quadrotor system with two degrees of underactuation. A Lagrangian system based on virtual angles is developed for the quadrotor. Based on the model, the matching conditions presented by nonlinear partial differential equations are explicitly solved for the nonlinear quadrotor system without decoupling or division. Besides, it is demonstrated that a constant controlled kinetic matrix could be utilized for energy shaping and simplify the matching conditions since gyroscopic force terms are omitted. Smooth state feedback control laws guaranteeing asymptotic stability of quadrotor system are obtained. Stability analysis and range of the control parameters are deduced based on the reshaped closed-loop energy. Simulation for a quadrotor helicopter shows the feasibility and efficiency of the theoretical results.