To improve the working efficiency of the in-situ soil remediation equipment, this paper takes black soil particles as the object, and the structural design of the new chain plate soil remediation equipment is carried out based on Solidworks.The mixing process of soil and chemicals under different parameters was investigated using the discrete element method and the orthogonal test method. The experimental designs were all based on horizontal movement speed, chain knife speed, screw speed, and uniform mixing distance as test factors and discrete coefficient and soil fragmentation rate as indices. The test method uses a unidirectional test to determine the value of the reference centre level for the orthogonal test and a combined balancing method to determine and validate the optimum parameters of the soil remediation device. The optimised parameters were determined as follows: the horizontal movement speed of the mechanism is 0.15 m/s, the rotational speed of the chain knife is 5.25 m/s, the rotational speed of the screw is 187.5 rpm, and the homogeneous mixing pitch is 98mm, respectively. The dispersion coefficient was reduced by 7.43% and the soil fragmentation rate increased by 5.45% compared to the operating parameters of the baseline group.