Abstract: The effecting factors of foamed cement pore structure are systematically researched. The results indicate that the water cement ratio, thickening agent, waterproofing agent and fly ash dosage are the main factors affecting the pore structure of foamed cement. Through changing the water cement ratio, thickening agent and waterproofing agent dosage, the pore size of foamed cement can be controlled. The compressive strength of foamed cement is relative to the pore size, and the optimum pore size has a certain range. The mix proportion of foamed cement is proposed which has higher compressive strength and proper pore size.