The invention discloses a method for dyeing fabrics by using borohydride, bisulfite and thiourea dioxide (TD) as composite reducing agents. Wherein, bisulfite and borohydride are used to prepare dithionite, and its consumption is half of that when not mixed with thiourea dioxide, and the consumption of thiourea dioxide is about one-tenth of that of dithionite. Compared with the dyeing method using only dithionite as reducing agent, the method has no obvious difference in dyeing effect, but the reducing agent used is relatively safer, more stable, has higher utilization rate, and has greater economic value. At the same time, the fabric dyed by this method has good level dyeing property and washing resistance, and is an ideal dyeing method.