In practical applications, the traditional cascaded H-bridge converter-based electrolytic hydrogen production system frequently encounters challenges due to uneven junction temperature distribution within the converter. In response to this issue, a single vector model predictive control for cascaded H-bridge converter-based electrolytic hydrogen production system considering the junction temperature equalization is proposed in this paper. Firstly, a discrete predictive model for model predictive control is established to obtain the optimal level number. Based on the theory of voltage vector simplification, the voltage vector is simplified. Secondly, use the DC side support capacitor voltage sorting algorithm for voltage sorting, and select the optimal simplified voltage vector based on the optimal level vector. Thirdly, using the proposed junction temperature equalization method, dynamically adjust the switching state of the zero vector in the optimal simplified voltage vector. Finally, the effectiveness of the junction temperature equalization method was confirmed through comprehensive simulations under various operating conditions.