The invention discloses a preparation method for trimethylethoxysilane, which comprises the following steps: (1) adding trimethyl chlorosilane into a reaction kettle, and then adding an absorbent capable of absorbing chlorine hydride by stirring, wherein the addition of the absorbent is 20 to 70 percent of the weight of the trimethyl chlorosilane; (2) dripping ethanol in the stirring process, controlling the dripping speed to enable the reaction temperature to less than or equal to 80 DEG C, and continuously stirring the mixture for 1 to 4 hours, wherein in the reaction, the addition of the ethanol is 1.10 to 1.20 times of the theoretically calculated molar mass; (3) after the reaction is completed, stopping stirring, standing the mixture for 5 to 30 minutes, performing natural layering on the product, and performing layering and separation to obtain a crude product of the trimethylethoxysilane in the upper layer. The method adopts the absorbent capable of absorbing the chlorine hydride, so that the reaction is performed smoothly under the condition of normal temperature, and the reaction is simplified and saves energy. The process is simplified, has high product yield, and reduces the extraction of a large amount of salt and volatilization loss so as to reduce the production cost greatly.