The invention discloses a method for producing low-pigment xanthan gum by fermenting cell wall defective cells of xanthomonas campestris 1.1781 and belongs to the technical field of biological engineering. The xanthomonas campestris 1.1781 preserved in China General Microbiological Culture Collection Center is used as a starting strain and a cell wall defective mutant strain is obtained through acontinuous passage manner; sucrose is used as a carbon source and raw materials including yeast powder, diammonium hydrogen phosphate and the like are added; the mixture is fermented and cultured for80h to 100h under an aerobic condition and an environment with the pH (Potential of Hydrogen) of 5.5 to 7.5 to obtain a product xanthan gum. The yield of liquid fermentation culture can reach 32g/L offermentation solution; the conversion rate of the raw material sucrose can exceed 90 percent. After the fermentation solution of the cell wall defective cells is diluted, OD560 value is measured andthe result is 0.051; an OD560 measurement result of an original strain fermentation solution is 0.296 and the result shows that the content of pigments is greatly reduced.