Modern tunnel construction requires excavation methods with high excavation efficiency, construction safety, and good tunnel quality. The excavation methods of Tunnel Boring Machines (TBM) meet the needs of efficient and safe construction. The excavation methods of tunnels are gradually shifting from traditional drilling and blasting methods to TBM and shield tunneling methods.In recent years, many large-scale tunnel projects have adopted the TBM excavation method for construction, but tunnel mud and water inrush accidents pose huge challenges to the safety of TBM tunnels. At present, there are two prediction methods for TBM tunnels: one is seismic methods, such as TRT. This type of method has achieved good results in the detection of unfavorable geological bodies such as fractured zones, faults, and fractured zones, but seismic methods are powerless in detecting water hazard geological bodies. Another type of electromagnetic method, such as induced polarization method, has achieved good results in TBM tunnel advanced detection. However, due to the limitations of this method, the detection distance and resolution are limited, and there is still significant prospect for development. The classic transient electromagnetic method, due to its use of magnetic source excitation, can only be applied in tunnels without TBM machine construction. At present, the advanced prediction work of TBM tunnels faces practical problems such as strong background interference and limited detection space, making it difficult for electromagnetic detection methods to be used in such environments. This article focuses on the structural characteristics of water-bearing karst caves and uses the three-dimensional vector finite element method to design a multi radiation source detection model on the TBM tunnel face. By applying transient electromagnetic radiation to parallel electrical radiation sources while receiving the x component of the electric field, multiple radiation sources can irradiate the same target from multiple angles. The simulation results show that multiple radiation sources are conducive to detection in strong interference and small space environments, It has good resolution ability for geological bodies with poor water content in karst caves.