The invention provides conjugate polyether, comprising 6-8 parts of polyether polyol EP-330N, 2-4 parts of polyether polyol SU-450L, 0.06-0.15 parts of non-hydrolytic surface active agent, 1.5-2 parts of water, 0.8-1.5 parts of nonyl phenol polyoxyethylene ether NP-10, 0.03-0.05 part of foaming catalyst PC52, 0.3-0.5 part of foaming catalyst NE300 and 1.3-2 parts of ethyl diethyl phosphate. The invention further provides a polyurethane raw material composition, polyurethane foams and applications thereof. Compared with the conventional polyurethane foams, the polyurethane foams in the invention have low density, low mass, proper aperture ratio, good sound-proofing effect, and good heat insulating effect, and compared with the polyurethane foams with middle and high density, the cost of the polyurethane foams in the invention is lower. While the polyurethane foams in the invention have low density, the polyurethane foams can reach the application standards of thermal insulation materials, sound-proofing materials, sandwich panels for construction, spraying materials for ceilings of automobiles or filling materials and the like. The conjugate polyether is a total-moisture foaming system, has no damage to ozone layer and has the advantage of environmental protection.