Chemical fungicides can effectively prevent and control powdery mildew, but they can also leave pesticide residues in the environment and on cucumbers. In this study, we added sulfur powder to the soil where cucumbers were grown to see how it affected the occurrence of powdery mildew. The results showed that adding sulfur increased sulfur absorption by the cucumbers, improved plant immunity, and reduced the incidence of powdery mildew. Furthermore, adding sulfur to the soil increased soluble protein content in cucumber leaves, enhanced photosynthesis, and significantly increased fruit yield. Additionally, sulfur addition decreased soil dehydrogenase activity and increased sucrase activity, potentially impacting soil microbial activity. In conclusion, this study found that adding sulfur had a positive inhibitory effect on the occurrence of cucumber powdery mildew while not significantly impacting the soil environment. These findings provide valuable insights for developing new control methods that are easy to implement, cost-effective, reliable, and environmentally safe.