The invention provides a method for dyeing a modified cellulose fiber textile by a rhubarb and turmeric dye. The method comprises the following: 1. a step of modifying a quaternary ammonium group of the cellulose fiber textile, in which a modifying agent with a concentration of 50 to 60 g / l and sodium hydrate with a concentration of 12 to 18g / l react for 40 to 60 minutes at a temperature of between 64 and 75 DEG C, the bath ratio is 1:30; in the post treatment after the modification, the fiber textile is washed by hot water at a temperature of between 40 and 50 DEG C for 10 minutes, is washed by cold water, is prickled by HAC with a concentration of 2 to 3g / l for 2 minutes, is washed by water to be neutral and is dried; 2. a step of preparing the dye solution by the sodium hydrate extracting agent with a concentration of 15 to 45g / l; and 3. a step in which the modified cellulose fiber textile is dyed, washed by water and dried directly by the dyeing technique and is washed by soap, washed by water and dried. The technique is simple and easy to implement, does not need the mordanting and the fixation processes and the like, has high rate of dye-uptake, good dye quality and the friction resisting color fastness and the colorfastness to washing up to more than three grades, is nontoxic, does not pollute the environment, and has low cost, and remarkable economic benefits and environmental benefits.