Superoxide dismutase is a cellular antioxidant with promising applications in food， cosmetic and pharmaceutical industries. In this study， based on the codon preference and efficient expression pattern of Pichia pastoris， the superoxide dismutase afSOD gene from Aspergillus fumigatus was optimized to reduce the GC content from 59% to 41%， and the CAI value was optimized from 0.69 to 0.96， and the gene sequence identity before and after the optimization was 73.8%. The recombinant strain induced an enzyme activity of up to 213.78 U/mL for 72 h. The recombinant enzyme AfSOD had the highest catalytic activity at pH 8.0 and 40 ℃， and was stable in a neutral environment and at 40-50 ℃. The promotion of the enzyme activity by the metal ion Cu2+ was particularly significant， with 5 mmol/L of Cu2+ increasing the enzyme activity by 80%， whereas Fe2+ showed a significant inhibitory effect. The recombinant enzyme AfSOD showed a significant scavenging effect on DPPH and hydroxyl radicals up to (97.65±1.46)% and (89.48±2.53)%. In addition， the efficient expression of recombinant enzyme AfSOD significantly enhanced the tolerance of yeast strains to temperature， osmotic pressure， salt， acetic acid and ethanol. This study not only provides some technical support for the efficient preparation of superoxide dismutase， but also provides theoretical support for the enhancement of yeast production tolerance.