Root rot is a serious disease in Dendrobium officinale planting. In order to provide data for control on root rot of Dendrobium officinale in field, the biological characteristics and effective fungicides screening of Fusarium oxysporum were determined indoors. The results showed that the optimal temperature for mycelial growth, sporulation and spore germination of Fusarium oxysporum was 25 ℃. Most of spores could germinate when the relative humidity was over 75%. The optimal pH of mycelial growth and sporulation was 7, the optimum carbon and nitrogen sources for mycelial growth were respectively fructose and sodium nitrate. The illumination conditions had no significant effect on mycelial growth and spore germination; the lethal temperature of conidia was 55 ℃ for 10 min. Indoor toxicity tests of nine fungicides demonstrated that the bioactivity against Fusarium oxysporum were: metalaxy-m mixed fludioxonil ＞ myclobutanil ＞ thiodiazole-copper ＞ propiconazole ＞ hymexazol ＞ tebuconazole ＞ triadimefon ＞flusilazole ＞ mancozeb. And the metalaxy-m mixed fludioxonil, myclobutanil and propiconazole were most effective to Fusarium oxysporum, which would be used as a reference for field control of this disease.