Abstract: The compressive strength test and chloride ion penetration resistance test were carried out on the foam concrete. The effects of dilution factor of foaming agent, water-cement ratio and foaming liquid concentration on the compressive strength, unsteady chloride ion migration coefficient and porosity of foamed concreteto were studied. The feasibility of foam concrete as a protective layer aimed at improving the resistance of ordinary concrete to chloride ion penetration was verified. The results show that when the dilution ratio of the dilution multiple is 60 times, the water-cement mass ratio is 0.5, and the mass fraction of foaming agent is 0.6%, the foamed concrete has the best resistance to chloride ion penetration, and its unsteady chloride ion migration coefficient 5.81×10^-12 m²/s.