The invention discloses a quantitative liquid feeding device and a use method thereof. The quantitative liquid feeding device comprises a shell, wherein a liquid feeding pipeline is connected with the top of the shell; a quantitative liquid feeding component and a lifting component are arranged on the shell; the quantitative liquid feeding component comprises a flexible liquid storage container and a liquid collection container; the quantitative liquid feeding component and the lifting component are matched with each other; the quantitative liquid feeding device is further connected with a stirring structure. As a liquid component which accounts for a relatively large percentage is added into a reaction kettle in different batches and is combined and stirred with other components, that is, small equivalent parts of the liquid component are added into the reaction kettle when being stirred, the stirring efficiency can be improved, the components can be stirred and combined uniformly, the product pass percentage can be increased, and meanwhile, an effect of preventing waste can be achieved.