Abstract: The strata of Lianlin highway foundation are made up by marine soft soils and characterized by high moisture, salt content and compression. The roadbed is strengthened by the mixed cement pile. This paper analyzes the strength characteristics of mixed cement pile in the marine soft soil. The indoor experiment results indicates that the strength of the cement-soil increases with the increment of the cement content. In the water-saturated state, the strength of the cement-soil increases within 28 days, but increases little after 28 days. The water content influences the intensity of grouted soil negatively. The wave velocity and the strength of the cement-soil from borehole are high in the upper and low in the lower of the pile.