Abstract: Many important soft soil projects need to be repaired quickly after failure, such as foundation pits and subgrade engineering. The appearance of magnesium phosphate cement satisfies the requirements of modern construction. However, the difference of the organic content of soft soil in different regions has an important influence on the properties of the solidified soil. We prepare soil samples with different organic contents by adding humic acid to the soft soil and study the reinforcement of soft soil with different organic contents by magnesium phosphate cement, contrast with the reinforced soft soil of PO cement under the same conditions. Finally, the following laws are obtained through the relevant mechanical tests: in the process of strengthening different organic contents of soft soil, the reinforcement effect can gradually decrease with the increase of organic content. Magnesium phosphate cement is obviously superior in rapid repair and condensation than PO cement. But long-term reinforcement effect of the magnesium phosphate cement in soft soil is not as good as that of PO cement. At the same time, SEM test is used to explain the obtained rules and analyze the microstructure evolution characteristics. Magnesium phosphate cement can be applied to the construction of soft soil repair projects. The research results uniquely analyze the influence of organic content change on the strengthening effect of magnesium phosphate cement, which has guiding and reference significance for reinforcing soft soil projects.