The invention discloses a preparation method for silver nanowires. According to the method, a hydrothermal reaction method is adopted, gallic acid serves as a reducing agent, by means of silver chloride generated through the reaction, silver ions with relatively low concentration are dissociated to effectively control a reaction speed of a system, and the silver nanowires with the relatively highyield are successively prepared. According to the preparation method, the process is simple, the number of the steps is small, conditions are gentle, operation is easy and convenient, constitutes arecontrollable, a conductive thin film prepared through the silver nanomwires made based on the method is good in electrical conductivity, and square resistance of the conductive thin film can reach 0.05+/-10% omega /sq.