Abstract: A structural dynamic system has multiple inputs and outputs.To establish an identification model that can precisely reflect structural dynamic characteristics is the key factor to realize valid vibration control with high quality.In this paper,a kind of multi-branch BPNN identification model is proposed.To enhance training efficiency and prediction precision,structural status variable and earthquake inputs,which affect structural dynamic response,are treated as respective branches and inputted into the model.The trained model is used to predict structural dynamic response under different earthquake in order to validate the generalization ability of the model.Numerical analysis shows that the proposed multi-branch BBNN model can identify the dynamic characteristics of a structural dynamic system and predict the structural dynamic response with high precision.