The invention discloses a scouring agent for fabric pretreatment and a preparation method thereof. Most of the existing products contain phosphate or other phosphorus substances which directly causes phosphorus environment pollution and water body eutrophication. The preparation method comprises the following steps: putting isomerous alcohol ether carboxylate, alkyl glucoside, isomerous polyoxyethylene ether and water into a reaction kettle according to a formulation proportion, stirring and mixing the mixture for 20 to 40 minutes within 40 to 50 DEG C at normal pressure, and preparing the non-phosphate scouring agent. The scouring agent does not contain phosphorus elements or APEO and has excellent alkali resistance, excellent alkali penetrability and excellent emulsifying dispersivity, therefore, the non-phosphate scouring agent has high efficiency and protects the environment.