The invention discloses an environment-friendly synthesis method for diphenyl phosphine chloride and aims to solve the problem of environmental pollution in the conventional process. The method comprises the following steps of: adding phosphorus trichloride, benzene and aluminium trichloride into a three-mouth bottle respectively; introducing nitrogen for protection; stirring intensely; heating to 140 to 150 DEG C; maintaining reflux; discharging a large amount of white smoke until the white smoke disappears; cooling to room temperature; and performing aftertreatment operation comprising the steps of adding an organic solvent into reaction liquid in the step A, stirring for 0.5 hour, adding a decomplexing agent beta-chlorophosphate triethyl ester dropwise for 0.5 hour, stirring for 1.0 hour, standing for 1.0 hour, removing the lower layer of the decomlexing agent layer, distilling the organic solvent layer under reduced pressure to obtain a crude product diphenyl phosphine chloride, and distilling the crude product diphenyl phosphine chloride under high vacuum to obtain the pure product diphenyl phosphine chloride. By the method, the aluminium trichloride is recovered through an environment-friendly idea, so environmental pollution is reduced, a byproduct is increased, and yield is increased. The method is high in yield, low in cost and short in reaction time.