Digital reading is now an important way for children to read. This article defines the concept of children's digital reading based on the current situation, reading needs, and research progress of reading promotion methods. Aiming at the problem that only simple matching method is used for entity extraction in BAG model, this paper proposes an entity extraction method based on reference words and an entity graph construction method based on problem-related entities. Experiments on data sets verify the effectiveness of the model. The results show that the BAG model is improved by 2.4% on the verification set and 4.1% on the test set, which proves the effectiveness of the improved method. Based on the graph convolution algorithm of the central node, the local subgraph convolution and the global graph convolution are connected in the entity graph behind the central node, so that the model can obtain local and global information at the same time and enhance the reasoning ability of the model.