Single factor test was applied to study on the engineering properties of modified raw soil, by which the reasonable range of grass, cement, quick lime, and fly ash were determined. The effects of various factors on the bending strength of modified raw soil were studied by orthogonal test method, and the experimental results were analyzed. The experimental results show that the order of influence on the bending strength of modified raw soil block was glass A> cement C> quick lime D> fly ash B. Finally, the optimal mixture ration of modified raw soil was determined.