A bulk power system is conventionally characterized by a complex structure with a large number of components. Each component generally has a different contribution to the transmission congestion (TC) of a system. Thus, a TC sharing method that can be used to evaluate the contribution of each component to the system TC and recognize the weak parts from the perspective of TC should be built. This paper presents a transmission congestion tracing (TCT) principle based on the failed component sharing principle and proportional sharing principle and a TCT model using the Monte Carlo simulation method. Case studies on the IEEE Reliability Test System indicate that the proposed method is effective and feasible.