The invention relates to a method for synthesizing phosphite ester compounds through esterification. Generally, phosphorus halide and alcohol or phenol are adopted for reaction. Taking monohydric alcohol as an example, the reaction equation is as follows: PCl3+3R-OH->P-(O-R)3+3HCl, wherein R is organic group, such as alkane, cycloparaffin, arene and the like. The equipment for the method comprises a reaction kettle, a tower, a circulating pump, a mixer, a heat exchanger and the like. The method has the beneficial effects that HCl generated by reaction is removed timely through the action of reactive rectification coupling, so that the reaction speed is greatly improved, ammonia hydrochloride or amine hydrochloride is prevented from generating due to addition of acid-binding agent, and the production cost of the existing technology is greatly lowered.