[Purposes] The paper aims to solve the poor engineering problems such as slurry turning and frost heave in the low liquid limit silt roadbed in the Northeast China. [Methods] A new type of aluminum tripolyphosphate (AT) curing agent based on water glass was used to improve the low liquid limit silt. The unconfined compressive strength test was carried out on the AT-solidified soil and compared with the water glass-solidified soil under the condition of curing for 28 days. Simultaneously, the freeze-thaw cycle test was carried out. Additionally, X-ray diffraction（XRD) and scanning electron microscope test (SEM) further explored the microscopic mechanism of its strength formation and freeze-thaw resistance. [Findings] The unconfined compressive strength of AT-solidified soil increases with the increase of the curing agent content, the compaction degree and the curing age; the unconfined compressive strength of AT-solidified soil with different curing agent contents tends to be stable after 7 times of the freeze-thaw cycle; compared with water glass, AT curing agent can produce more silicic acid gel and aluminum silicate produced by the reaction can effectively improve the water resistance and the unconfined compressive strength of the silt. [Conclusions] Compared with water glass, AT curing agent can improve the freeze-thaw resistance of silt, and AT-solidified soil has better mechanical properties.