In order to comprehensively utilize construction wasteland and replace sand and gravel aggregates, a new type of backfill material (controlled low strength materials, CLSM) with high fluidity and low bleeding rate is prepared. Through the fluidity, bleeding rate, wet density and unconfined compressive strength test, the effects of water-binder ratio, cement content and wasteland content replacement on the physical and mechanical properties of CLSM were discussed. Combined with EDS spectrum analysis and SEM test, the mechanism of strength influence was further revealed.The results show that: the water-binder ratio mainly controls the fluidity of CLSM. With the increase of the wasteland content, the water-binder ratio that meets the flowability of the material continues to increase, and the addition of wasteland greatly reduces the bleeding rate of the material. The amount of cement in the material affects the development of CLSM strength; through microscopic analysis and calculation, it is concluded that the formation of soil-based CLSM strength is mainly due to the hydration reaction, agglomeration of cement and the bonding of clay particles. This paper provides a research idea for the preparation of CLSM using construction wasteland, and prepares CLSM with excellent working performance for future engineering trench backfill.