Abstract: The conifer sawflies are economically important defoliators in the forest in Yunnan Province.A classification of larvae of Diprionidae in the province is conducted for the first time on the basis of their adult taxonomy.The larvae are identified as conspecific with adults through rearing larvae to adults.In this part,history of larvae classification is reviewed.External morphology of larvae is described.A key to the 5 genera of larvae of Yunnan Province is prepared.Host plants of each genera are recorded.Color of head capsule and thoracic legs,color patterns of body,the presence or absence and number of glandulae on skin are important characteristics for genera and species separation.