About system state equation solution of the nonhomogeneous term of the precise integration method which involves the matrix inversion and calculation accuracy depending on the nonhomogeneous term fitting precision, an improved gaussian precise integration method, by combining the GaussianLegendre integration with the piecewise spline interpolation method, is proposed. In the new method, using the precise integration exponential matrix to solve the coefficient of the Gaussian integral precisely, and using the spline interpolation function to determine gauss integral points of discrete load within each time step length. Newmarkβ method, the traditional precise integration method and the improved gaussian precise integration method of this artical were used respectively to calculate time response of the Rayleigh damping models cantilever beam system by external load, and compared with the calculation result of modal superposition method. The result demonstrates that the improved Gaussian precise integration method has high precision, high efficiency and is not limited strictly by the integral time step.