The coating line generally compares the coating consumption and cost of different suppliers according to the formula "coating consumption per unit area=coating film thickness multiplied by the density of the dry coating film and divided by the coating efficiency and divided by coating solid fraction".Among them,the density of the dry coating film is calculated theoretically by the coating supplier according to the empirical formula and then provided to the factory,but the theoretical calculation results of different coating suppliers often deviate greatly.In this paper,according to the principle of the density of suspended solids in liquid is the same as that of liquid,we provide a method for measuring the density of dry film for production site implementation.