The present invention relates to the technical field of carbonless papers, in particular to a coating formula for a jet-printed non-color-developing side of a carbonless paper used in the aqueous ink jet printing of bar code symbols. Calculated according to weight portions, the coating formula contains the following ingredients: 700 to 900 portions of water, 2 to 10 portions of dispersant, 50 to 70 portions of kaoline, 90 to 110 portions of calcium carbonate, 125 to 140 portions of laminating adhesive, 3 to 10 portions of polyvinylpyrrolidone, 3 to 5 portions of optical brightener and 2 to 5 portions of foam suppressor. When aqueous ink is used to jet-print the carbonless paper adopting the jet-printed non-color-developing side and coated with the coating formula to print bar code symbols, the problems of the diffusion and deep permeation of the aqueous ink on the coating of the carbonless paper and the nicks on the edges of ink lines can be effectively resolved, so that the quality of the reflection curve of a bar code can come up to the class A of the national standard.