This paper proposes a three-level bidirectional Buck/Boost converter based on TCM (Triangular Current Mode) soft-switching control scheme, which can realize zero-voltage turn-on of all switching transistors in the full load range without adding resonant components. This paper analyzes the working principle of TCM mode and proposes the critical conditions for implementing soft switching. When the three-level bidirectional Buck/Boost converter is stable, its flying capacitor voltage must be maintained at half of the bus voltage. Therefore, a closed-loop regulation mode based on the fly-capacitor decoupling control combined with the TCM mode is proposed. The closed-loop simulation with MATLAB verifies the steady-state and dynamic performance of the entire system operating in Buck mode and Boost mode.