Artificial intelligence （AI） technology has not only changed the production mode of human beings， but also reshaped the way human beings to solve social problems. The traditional social innovation theory born in the industrial era has gradually lost its explanatory power， and academics have put forward a new task of reconstructing the social innovation theory in the age of AI. Building on comparing traditional social innovation and digital social innovation， it suggested the new connotation of AI social innovation， so as to construct the social innovation theory in the age of AI. It emphasised that AI social innovation helps to intelligently identify floating social problems， promote the optimal matching of solutions， and accelerate the diffusion of social innovation. Building on the role of AI on matching social problems and solutions in social innovation process， it took the urgency of social problems and the novelty of solutions as the analytical framework， and proposed， for the first time， four AI social innovation models， including AI-autonomous searching， AI-augmented generative， AI-autonomous patching， and AI-augmented exploratory social innovation. These findings expand the connotation of existing social innovation theories.