Abstract: To explore the biological characteristics of Phytophthora nicotianae, a pathogen of heart rot of pineapple in Hainan, effects of different culture medium, temperatures, pH value and illumination on the mycelial growth and sporangium production of pathogen were studied. The results showed that V8 juices and carrot culture medium were suitable for mycelial growth, and V8 juices, corn and tomato culture medium were suitable for sporangium production, especially massive sporangium could be inducted in tomato culture medium. The pathogen could grow under 1035C with optimum temperature range of 24，32，C. The optimum pH was 5，8, mycelia grew fastest when pH value was 7，8. Illumination had no significant effect on mycelial growth of the pathogen, but obviously promoted sporangium production