The invention discloses a device and a method for mixing and reacting halogenated silane with a reaction medium for making the halogenated silane contact the reaction medium fully and react with the reaction medium completely so as to improve the quality of the reaction product. In the reaction device, the halogenated silane and the reaction medium are mixed at an entrance of a halogenated silaneloop; the entrance of the halogenated silane loop is formed in a connection pipeline between a supply port of the reaction medium and a forced circulation device, or at an entrance of the forced circulation device; and a dispersion device is also arranged between a supply port of the halogenated silane and the entrance of the halogenated silane loop. In the reaction method, a structural formula of the halogenated silane is RySiX4-y, wherein R is CnHm; n is an integer of more than or equal to 0; m is the integer of more than or equal to 1; y is equal to 1, 2 or 3; and X is a halogen atom; the reaction medium is water, aqueous solution of hydrochloric acid and the like; after the halogenated silane is dispersed by the dispersion device, the halogenated silane is mixed and reacted with the reaction medium at a turbulent area of the reaction medium; and the dispersion device is a liquid phase distributor or a spray nozzle and the like, and is particularly suitable for hydrolysis reaction of the halogenated silane.