The invention relates to a one-bath dyeing deoiling agent capable of reducing energy consumption, improving efficiency, saving cost and reducing COD (chemical oxygen demand) of wastewater and a usingmethod of the one-bath dyeing deoiling agent. The one-bath dyeing deoiling agent comprises the following components: sodium carbonate, sodium silicate, sodium dodecyl benzene sulfonate, sodium dodecylsulfate, fatty acid methyl ester sulfonate, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether sodium sulfate and a dispersing agent. The pH value of the one-bath dyeing deoiling agent is controlled between 9 and 9.8, and the one-bath dyeing deoiling agent has a good alkali function; the one-bath dyeing deoiling agent has the advantages of high emulsification, dispersion, deoiling, decontamination, cylinder cleaning and anti-back-sticking effects, and KF-22 one-bath dyeing deoiling agent can reduce the color point and the color staining probability by 40% or above on year-on-year basis through actual production long-time effect authentication. According to the dyeing product quality test, the color difference of a dyed product is greater than or equal to grade 4, thecolor fastness to water is greater than grade 3, the frictional color fastness is greater than or equal to grade 3.5, and the color in the same type is consistent with that of a process of desizing and then dyeing.