Abstract: Under the random vehicle loading condition, according to the dynamic characteristics of soil, the active patterns of soil and the violation for retaining walls were analyzed in a rudimental procedure. Based on the Rankine active earth pressure theory and the limit equilibrium condition of retaining walls, three parameters were introduced into the program of instability analysis. Carrying the critical anti-sliding force and anti-sliding moment as analytical formulas, and taking into account the limit equilibrium condition of the wall-soil system, two equations were well established. A practical engineering was analyzed by this method and numeriacl analysis. The result shows that the angle of sliding wedge of subgrade soil are almost in the same value with different analytical measurements.