Abstract: The inhibiting effect of citronella essential oil on fungi in the air was studied, so as to provide basis for improving the home environment, work environment and physical conditions of people. In this study, citronella essential oil was used as the material, and the indoor microorganisms were bombarded on the culture medium by adding citronella essential oil and indoor fragrance diffusion, in order to observe the growth of fungi. The results of antibacterial test of adding citronella essential oil to the culture medium showed that compared with the control group (without citronella essential oil being added to the culture medium), the treatment with the content of 0.02% essential oil had no significant difference in the inhibiting effect on fungi, while compared with the control group, the inhibiting effect of the treatment with the content of 0.06% essential oil, 0.12% essential oil, 0.18% essential oil and 0.24% essential oil on fungi all reached the extremely significant level. The results of bacteriostatic test of the length of indoor fragrance diffusion showed that, with the extension of time, the growth of microorganisms in the air was slow, and the treatment time of 1 h, 2 h, 3 h and 4 h all had obvious antibacterial effect. With the extension of time, the antibacterial effect basically tended to be the same. Citronella essential oil could had inhibiting effect on fungi in the air, and had a significant inhibiting effect on fungi in the air after 1-2 h of fragrance diffusion.