Facing challenges like national energy security, China must construct a green, low-carbon energy system. In the future, China’s power system will see a high proportion of new energy grid connection. Due to the intermittent and volatile output of new energy sources, stability issues will arise. Thus, a reasonable assessment of DC carrying capacity is crucial for grid safety and stability. With transient overvoltage as the starting point, this article focuses on the evaluation method of DC carrying capacity: Study the calculation methods of transient over-voltage and voltage rise at the converter station bus. Analyze the relationship between transient over-voltage and its main influencing factors. Finally, based on the research of transient over-voltage, the evaluation method of DC carrying capacity is studied. The relationship between DC transmission power and transient over-voltage and voltage rise at the converter station bus is studied in PSASP to verify the effectiveness of the evaluation method for DC carrying capacity. With the threshold of transient voltage rise as a constraint, the DC carrying capacity under different short-circuit capacities is evaluated.