In order to solve the problems of low image 
information hiding capacity and 
distortion in the aspect of 
data privacy protection, the invention provides an 
information hiding method, device and 
system based on a cavity spatial 
pyramid, which are used for embedding and extracting 
watermark information in a protected image to realize image version 
authentication and protection. According to the method, a cavity space 
pyramid module is built by adopting cascaded and parallel cavity 
convolution layers, the 
receptive field is expanded, the multi-scale and multi-cavity-rate characteristics are extracted, information is more accurately hidden in a semantic redundancy position, and the decoding capability of a 
network on embedded information is improved; meanwhile, the decoding accuracy is improved by using 
cross entropy loss; in addition, the quality of the generated image is improved through residual error and 
linear operation confrontation in the discrimination network; finally, in order to improve the network stability, updating of different scales, cosine annealing adjustment and an intensive connection strategy are used in training. According to the method, high-capacity 
information hiding is achieved, meanwhile, it is guaranteed that images are not distorted, and experiments prove that the method has high information hiding capacity.