The invention discloses a colored wide and dense cotton belt and a dyeing method of the colored wide and dense cotton belt and belongs to the technical field of textile dyeing. The dyeing method comprises the following steps of (1) preshrinking the wide and dense cotton belt, wherein the wide and dense cotton belt is immersed in hot water with the temperature ranging from 50 DEG C to 90 DEG C for 15 to 50 minutes, and then dehydration is carried out, wherein the bath ratio is 1:5-20; (2) winding the belt, wherein the preshrunk wide and dense cotton belt is evenly wound around a dyeing shaft; (3) conducting pretreatment, wherein the dyeing shaft with the wound wide and dense cotton belt is placed in a dyeing device for pretreatment, specifically, the start pump speed of a water pump of the dyeing device is 10 percent to 15 percent of the maximum pump speed, the pump speed of the water pump is increased by 15 to 25 percent every 20 to 40 minutes, the pump speed is increased to 80 to 90 percent of the maximum pump speed finally, and pretreatment is carried out for 40 to 60 minutes at the final pump speed; (4) conducting dyeing, wherein the pretreated wide and dense cotton belt is dyed. By the adoption of the dyeing method, the obtained colored wide and dense cotton belt has the advantages of being even in color, free of wrinkles and folds. The dyeing method can be widely applied to dyeing production of wide and dense cotton belts.