In slope engineering, the shear resistance of rock and soil can never be exerted themselves by general pre-reinforced structure, through the coupling mechanism between reinforced structure and slope, an initiative decompression pre-reinforced structure consists of soft stuffing and pre-reinforced structure is presented. The setting and thickness of soft stuffing are both key questions during the design of initiative decompression pre-reinforced structure. On one hand, the setting of soft stuffing assure that parts of initiative decompression pre-reinforced structure cannot interact each other under reinforcing; on the other hand, the thickness of soft stuffing can assure that the shear resistance of rock and soil can be exerted by themselves, the sliding thrust which is endured by pre-reinforced structure alone is changed to be endured by soil and pre-reinforced structure together. Then the sliding thrust endured by pre-reinforced structure minimizes, accordingly the effect of initiative decompression is achieved. In the end, the calculation procedure of thickness is illustrated by a practical project and the result is rational.