Sign language recognition involves computer vision, pattern recognition, human-computer interaction, etc. It has important research significance and application value. The flourishing of deep learning technology brings new opportunities for more accurate and real-time sign language recognition. This paper reviews the sign language recognition technology based on deep learning in recent years, formulates and analyzes the algorithms from two branches - isolated words and continuous sentences. The isolated-word recognition technology is divided into three structures: Convolutional Neural Network (CNN), Three-Dimensional Convolutional Neural Network (3D-CNN) and Recurrent Neural Network (RNN) based method. The model used for continuous sentence recognition has higher complexity and is usually assisted with certain kind of long-term temporal sequence modeling algorithm. According to the major structure, there are three categories: the bidirectional LSTM, the 3D convolutional network model and the hybrid model. Common sign language datasets at home and abroad are summarized. Finally, the research challenges and development trends of sign language recognition technology are discussed, concluding that the robustness and practicality on the premise of high-precision still requires to be promoted.
