Abstract: A grain mildew detection method and device based on a WiFi apparatus. The method includes the following steps: acquiring a WiFi signal which passes through a grain region, extracting channel state information (CSI) amplitude data from the WiFi signal, and acquiring grain statuses corresponding to the CSI amplitude data; establishing a neural network model, and training the neural network model by using the acquired CSI amplitude data and the grain statuses corresponding to the CSI amplitude data, to obtain an amplitude-status relationship model; and acquiring a WiFi signal which passes through a region in which grain to be detected is located, extracting CSI amplitude data from the WiFi signal which passes through the region in which the grain to be detected is located, and inputting the CSI amplitude data into the amplitude-status relationship model, to obtain a grain status of the grain to be detected.