There were lots of studies reporting the toxic effects of formaldehyde on various organs of human and animals, but the differences of effects among various concentrations of formaldehyde were rarely reported. In this paper, we used Drosophila melanogaster as model organism, added different proportions of formaldehyde into the fly food, and observed the effects on life span and stress resistance. The results showed that the life span of female flies depended on the formaldehyde concentrations, 0.037% formaldehyde could significantly extend the life span of female flies, whereas the higher concentrations of formaldehyde (≥0.185%) could significantly reduce the life span of male and female flies. What's more, 0.037% formaldehyde significantly increased the starvation resistance and heat shock resistance, but reduced the oxidative resistance in both male and female flies. These results provided a new way to study the molecular mechanisms of longevity and stress resistance in Drosophila.