The work aims to prepare halogen-free rigid polyurethane foam (RPUF) by compound foaming with modified azodicarbonamide and water through the release of gases for foaming by thermal decomposition reaction of azodicarbonamide (AC), to explore the feasibility of modified azodicarbonamide in polyurethane foaming. By changing the amount of modified azodicarbonamide in the system, the effects of modified azodicarbonamide on the viscosity, mechanical properties and thermal conductivity of the polyether foaming system were investigated. The results showed that the addition of the foaming agent could significantly reduce the viscosity of the polyether system and improve the fluidity of the foamed material, and the viscosity of the system gradually increased with the increase of the amount of modified AC, and the lowest viscosity of the system was 2 080 when the amount of modified AC was 0.3 g. When the amount of modified AC was 0.75 g, the apparent density of polyurethane foam was 78.65 kg/m3, the compression strength was 539.35 kPa, and the addition of modified AC increased the thermal conductivity of polyurethane foam, which was 0.023 51 W mK-1. The addition of modified AC can obviously improve the compressive strength of rigid polyurethane foam. Compared with pure water foaming, the compound foaming performance of the two is superior and can be applied to polyurethane foaming as a halogen-free foaming agent.