The risk sources during excavation increase with the increase of depth and scale of excavation. A crisp number cannot identify the risk correctly, whereas fuzzy number is an effective way to identify characteristics of risk sources. This study proposed a coupled analysis model to identify risk sources quantitatively. The proposed model incorporates triangular fuzzy number into the technique for order preference by similarity to an ideal solution (TOPSIS). Based on construction practice and experts experiences, indexes of risk sources during excavation are summarized from three aspects, namely excavation characteristics, surrounding environment and construction management. Then, the risk sources identification model is established via integrating triangular fuzzy number into TOPSIS method. This model can consider experts' judgments to make the results more rationally than the traditional models. Excavation construction in Tianhe Road Station, Guangzhou is adopted as a case study. The evaluated results are consistent with engineering practice, which verifies the applicability and effectiveness of the proposed model. The model can provide a guideline in risk sources identification and management during excavation.