The development of brown spot needle blight of pines was investigated in young slash pine plantations in Fcngxin County, Jiangxi province in 1986-1989. The results showed that the disease index increased more rcpcadly in the middle of June to the middle July, and the next middle in September to October every year. The incidence increased gradually within 3-4 years after planting and decreased since the fifth year. The disease spread rcpcadly from the infection focus but with less damage.