In order to solve the problem that the weak mucky soil cannot be directly used for subgrade filling, it is necessary to explore an excellent curing agent formula. First，blast furnace slag, fly ash, and calcium carbide slag were selected as curing materials to reinforce the Taizhou mucky soild. Next, by texting unconfined compressive strength, the regression equations of 14 d and 28 d ages were obtained using the method of mixture test analysis. It was found that the mass fraction ratio of the curing agent which is called ZX20 at the best ratio was as blast furnace slag∶fly ash∶calcium carbide slag = 42.1∶11.5∶46.4. The strength of ZX20 solidified soil at 28 d age was 1 479.32 kPa. Then, by texting unconfined test, water stability test, and dry-wet cycle test on ZX20 solidified soil and limelime soil, the results showed that ZX20 solidified soil met the requirements of subgrade filling strength and had higher strength, better road performance water stability and dry-wet cycle than traditional lime-lime soil. Next, it was found that the logarithmic function had a good fit for the relationship between the strength of ZX20 solidified soil and age. Finally, by using the SEM method and PCAS software, the microscopic mechanism of ZX20 solidified soil was analyzed qualitatively and quantitatively. It was found that a large number of filaments, needles, and floccules were generated in the solidified soil with age, and the large pores were divided into small pores and filled partial pores, thereby increasing the strength of the solidified soil.