The present invention relates to the field of denim fabric processing, specifically to an environmentally-friendly processing method for dyeing denim fabric with zero discharge. The method includes: step 1, a treatment of white warp yarns; step 2, a primary drying operation; step 3, a coating spray-dyeing operation; step 4, a secondary drying operation; step 5, a sizing operation; step 6, a ternary drying operation; and step 7, a doffing operation. In the present application, as warp yarns are dyed using the coating spray-dyeing technology, highly corrosive auxiliaries such as sodium hydrosulfite and sodium sulfide are not needed in the dyeing process, and the dyed warp yarns are not required to be treated in a washing tank, so that zero effluent discharge is achieved.