This paper proposes a model and data hybrid-driven short-term voltage stability assessment method. First, a double-generator-one-load (DGOL) simplified model for short-term voltage stability analysis is introduced, and the mechanism of the occurrence of short-term voltage instability is analysed based on a DGOL model. Then, a model and data hybrid-driven online application algorithm is proposed, which includes a pre-fault analysis module and a real-time monitoring module. At last, a two-dimensional index is proposed to evaluate the short-term voltage stability margin. Simulation work is first conducted based on the DGOL system to illustrate the advantage of the proposed simplified model, and on the EPRI 36-bus system to demonstrate the effectiveness of online application algorithm.