The invention discloses a preparation method of a 
halogen-free environment-friendly 
polyurethane oil paint. The preparation method comprises the following steps: performing refluxing 
catalytic hydrogenation reduction on a phosphatizing agent and a 
nitrobenzene derivative in an 
organic solvent with the presence of a 
metal catalyst to obtain a phosphatized 
aniline derivative, dropwise adding 
trichloromethyl chloroformate, mixing and stirring uniformly at 
room temperature, reacting continuously for 2-4 hours to obtain phosphatized 
phenyl isocyanate, stirring the phosphatized 
phenyl isocyanate and an alcoholic compound for 3 hours with the presence of a 
polymerization catalyst, adding an amine compound, stirring continuously for 2 hours, performing vacuum 
dewatering on a reaction mixture to obtain 
flame-retardant 
polyurethane resin, adding a curing agent and a 
solvent, and reacting to obtain the 
halogen-free environment-friendly 
polyurethane oil paint. The invention further discloses the 
halogen-free environment-friendly polyurethane 
oil paint. The halogen-free environment-friendly polyurethane oil paint is an 
expansive environment-friendly 
flame-retardant polyurethane oil paint with a phosphorous-
nitrogen synergistic effect. In the production process of a 
flame retardant, raw materials are cheap and easily obtained; the preparation method is free of a high-heat and high-pressure process, and simple to operate, and 
energy consumption in the production process is low; the whole production process is saves energy and is environment-friendly.