Considering the characteristics of non-homogeneous external loadings in the state space formula conversed from structural dynamic equation, a new improved direct precise integration method is presented in this paper. Meanwhile, different improved formats for Duhamel integration are proposed based on the Trapezium formula、compound Trapezium formula、Simpson formula、compound Simpson formula、Cotes formula and Gauss formula. The precision and the efficiency of the calculation are examined under the different formats. The results of the case study show the validity of the improved method.