The invention provides an adaptive spatial steganographic method based on adjacent pixel difference. The method comprises the following two steps: embedding secret information and extracting the secret information. The method takes three continuous adjacent pixels in an image as an embedding unit and reaches the goal of hiding information by changing the value of the middle pixel in each unit. During information embedding, a steganographic algorithm always mains the size relationship of each pixel in the embedding unit, and adaptively adjusts the capacity of embedding information through a parameter according to the content of the image. Experiments show that the adaptive spatial steganographic method has higher safety and adaptive ability compared with the prior steganographic method based on pixel difference. Therefore, the adaptive spatial steganographic method has great practical significance to application fields such as covert communication and the like.