The invention discloses a micro-reaction method and device for synthesizing phosphoric acid tris(2-chloropropyl) ester (TCPP). The micro-reaction method is capable of using an esterified intermediateproduct as a solvent of phosphorus oxychloride and a catalyst, efficiently mixing epoxypropane and solution containing the phosphorus oxychloride and the catalyst through a micro-mixer, in a moderatereaction condition, completing preparation and circulation of the esterified intermediate product, and further completing a reaction of the esterified intermediate product and the epoxypropane througha multi-stage serial reaction kettle and forming the TCPP. The method is a continuous reaction process, a temperature is easy to control, formation of ethers by-products can be effectively inhibited,and product purity of the TCPP reaches 98% or more.