The invention discloses a method and spraying device for controlling gray mold based on electrolyzed functional water. The method includes the steps that 1, the electrolyzed functional water is sprayed to crops observed that the crops infect gray mold early; 2, the electrolyzed functional water is sprayed once every morning, noon and evening; 3, leaf surfaces are sprayed, then spraying is carriedout from tops of stems, and spraying is carried out in sequence from top to bottom; 4, forms of the crops are observed in the next day, and the step 2 and the step 3 are repeated; 5, the electrolyzedfunctional water is sprayed once night and morning in the fourth day till spraying is carried out in the fruit maturation stage. The method and spraying device are used for controlling gray mold through the electrolyzed functional water.