To understand the parametric effects on the performance of a molten sodium hydroxide direct carbon fuel cell, an experimentally validated mathematical model is established to investigate the influences of temperature, temperature distribution, anode rod radius, electrode spacing, and inner cell diameter on the cell behaviour. Mass transfer, heat transfer, and secondary current distribution theories are considered in the model cell. A high temperature, small anode rod radius, small electrode spacing, and small inner diameter of the cell are recommended to enhance the cell behaviour, which are conducive to the transmission of hydroxide ions (OH-) based on mass and heat transfer. The small temperature difference distribution in the cell has a weak effect on the cell performance, and the three-phase boundary is the key factor influencing the cell behaviour in all cases. An orthogonal test was conducted to determine the best parameter combination for the maximum cell performance, and the Pearson correlation coefficient was used to evaluate the relevance of the investigated parameters to the cell performance. The order of the influence of each factor on the maximum power density of the cell is as follows: temperature > anode rod radius > electrode spacing > cell diameter. When the temperature is 973 K, the anode rod radius is 0.55 cm, the electrode spacing is 2.2 cm, and the inner diameter of the cell is 5 cm, and the optimized power density is 25.40 mW cm(-2).