Abstract: This paper deals with the biology and management of the pine sawfly Diprion nanhuaensis Xiao, a serious leaf-infesting pest of Yunnan pine(Pinus yunnanensis Franch). The life history and other major biological characteristics of the pest are presented in the text. Management suggestions are made as follows:⑴ I mproving the silvicultural and managerial practices to accelerate the sapling growth of the host can minimize the hosfs suitability for insect egg-laying;(2) A good sanitation in the infested forest during, winter will keep down the pupal population of the pest;(3) Hand treatment of the aggregated larvae is found feasible. When necessary, a dosage of emailsified D D V P will give a good control of larvae. Under a suitable temperature and humidity condition, the Beauveria bassiana preparation is found effective for suppressing the larval population; and(4) Some phenological phenomena are found helpful to monitoring the pest abundance and impplemen-ting timely control.