Aiming at the instability and slip in the deep soft foundation section of in-service highway, a quick treatment method of micropile with coupling beam at pile top is proposed. Combined with the actual project of soft foundation reinforcement in Kaiyang highway from mileage K3202+577 to K3202+640, the reinforcement techniques micropile and coupling beam are introduced. The measured deep horizontal displacement and settlement of soft subgrade are greatly reduced after reinforcement, indicating that this method can effectively mifigate sliding. The numerical analysis model for the deformation of deep soft foundation reinforced by coupling beams and micropiles is established by Plaxis 3D. The rationality of the model is verified by comparison with the field measured data, with influences of spacing, row spacing and form of coupling beam on treatment effect investigated. The results show that the lateral displacement increases with the increase of pile spacing, and when the pile spacing exceeds 10 times pile diameter, the soil lateral displacement increases obviously.The addition of coupling beam can reduce the lateral displacement of subgrade soil and optimize the stress of micropiles. The treatment effect of different types of coupling beams is ranked as follows:bidirectional cross coupling beam, followed by unidirectional cross coupling beam, then oblique coupling beam, while longitudinal coupling beam is the least. The conclusions can provide reference for the optimization design of similar projects.