To address the problems of soft soil cured by cement curing agent such as insufficient strength and poor integrity, a case study is conducted on Mangzhou tunnel in Zhuhai, China, and a newly developed soft soil curing agent is introduced to reinforce the soft soil layer. By analyzing the engineering characteristics and construction risks, the reinforcement mechanism of soft soil is explained by means of indoor and field tests. By setting the comparison indoor test between curing agent and cement content, the strength difference between the two is expounded through the 7and 28day unconfined compressive strength tests. The results show that: (1) The 28day unconfined compressive strength of the solidified body with 13% dosage of curing agent is 2.48 MPa, which is 91% higher than that with cement dosage of 20%. (2) The core sample of triaxial mixing pile reinforced by curing agent is complete, and the unconfined compressive strength values of each depth are greater than the design requirement of 0.8 MPa with a minimum value of 1.86 MPa and an average value of 2.47 MPa, fulfilling the design requirements. (3) The cost can be saved by 15%~30% compared with cement.