The red clay was applied to replace the peaty soil at a certain percentage, and the test study on the stabilized peaty soil was carried out with cement. The stabilized mechanism was discussed from macroscopical and microscopical aspects. The results show that the unconfined compressive strength of stabilized peaty soil increases firstly and then decreases with the increase of the replacement rate of red clay when the moisture content is the same.On the one hand, the replacement of red clay enables the particles to fill the soil pores as skeleton. On the other hand, the red clay reduces the organic matter content in the peaty soil and increases the Al content in the stabilized system simultaneously, which excites the activity of hydration and promotes the formation of ettringite. This can make the flocculent structure of peaty soil dense,the particles cementation and the pores filling optimized.