Synthesis method of bisphosphite

The invention discloses a synthesis method of bisphosphite. The method comprises the following steps of using phosphorus trichloride with a reagent amount, 2,2'-diphenol and 3,3',5,5'-tetratert-butyl-2,2'-diphenol as raw materials, dissolving the phosphorus trichloride in an organic solvent to form a solution, afterwards, adding an organic solution, in which the 2,2'-diphenol, an organic alkali and a catalyst are dissolved, under agitation, and after the addition of a phosphorus trichloride solution is completed, enabling a reaction solution to continuously react for several hours; adding an organic solution in which the 3,3',5,5'-tetratert-butyl-2,2'-diphenol is dissolved into the reaction solution, after the addition is completed, continuously agitating the reaction solution for severalhours, subsequently raising a temperature to 80 to 120 DEG C, and refluxing for several hours; after a reaction is finished, cooling reaction liquid to a room temperature, filtering, washing a filtercake, merging filtrate, th