The invention relates to washing powder containing alpha-sulfofatty acid alkyl ester salt and a preparation method thereof. The washing powder containing alpha-sulfofatty acid alkyl ester salt is prepared from the following raw materials in percentage by mass: 1.0 to 20.0 percent of alpha-sulfofatty acid alkyl ester salt, 1.0 to 12.0 percent of nonionic surfactants, 1.0 to 30.0 percent of anionicsurfactants, 1.0 to 10.0 percent of anticaking agents, 10.0 to 85.0 percent of washing auxiliary agents and 0.5 to 20.0 percent of pH regulators. The washing powder has the advantages that the material slurry is a neutral formula; the material preparation temperature, the material adding sequence, and the material slurry pH in the material slurry preparation process and spray drying process, and the tower entering and exiting temperature in the spray drying process are controlled, so that the washing powder containing alpha-sulfofatty acid alkyl ester salt has the advantages that the production process is simple; the anti-agglomeration performance is good; the stability of the alpha-sulfofatty acid alkyl ester salt in the washing powder is high.