With the rapid development of hybrid Modular Multilevel Converter (MMC), its efficient electromagnetic transient simulation is of great significance for safety and stability analysis related to DC engineering planning and design, scheduling and operation, as well as analysis of the interaction between AC and DC systems. The capacitor voltage sorting algorithm is the key to affecting the simulation efficiency of the electromagnetic transient model of hybrid MMC in the unlocking mode. This article studies the basic principle of heap sorting and derives its time complexity. Based on this, a capacitor voltage sorting algorithm of hybrid MMC based on heap sorting is proposed based on the modulation principle of the hybrid MMC unlocking mode, which effectively improves the simulation efficiency of the hybrid MMC electromagnetic transient model. Finally, a testing circuit is built based on the self-developed electromagnetic transient simulation software ESP, the effectiveness and accuracy of the proposed algorithm have been verified.