The sedimentation column tests and particle analysis experiments are performed on the waste slurry of a bored pile in Wenzhou to study the influence of organic flocculant APAM and inorganic flocculant CaO on the mud settling property and particle size. The influence of different addition order of inorganic flocculant CaO on the flocculation effect of organic flocculant APAM are focused on. The results show that: on the basis of less APAM addition (10mL), CaO adding can increase the mud initial sedimentation amount; adding CaO then adding APAM is not conductive to APAM flocculation; in case of adding CaO later, the effect of CaO on the final flocs particle size mainly depends on the strength of the floc itself and the stirring intensity.