Abstract: Insecticide smoke has been applied to forest pests in China for more than 20 years. It is widely used because it is easy to handle, high in efficiency and effective in results in large area control, with little pollution and residue. Recently fungicide smoke has also been employed to control forest diseases. Even the smoke of BHC has good results in Controlling Mycosphaerella larici-leptolepis Ito. Soto et oda., Lopho-aermium pinastri Chev., Pestaloizza sp., etc. But systematic studies have not been made yet. In the present study, We find out that 7 kinds of mixed fungicide smokes selected from 26 conventional kinds are more effective in controlling the main forest diseases, such as Scirrhia acicola ( Dearn. ) Siggers., Colletotrichum sp., etc. Their making-up and physicochemical properties have also been studied.1 . The chlorothalonil-carbendazol (S-791) and chlortohalonil-phaltan (S-792) mixture smokes have high toxicity on the conidium of Colletolrichum sp., inhibiting the germinating rate of conidium by over 95% under certain conditions. The Chlorothalonil-carbendazol (S-794) mixture smoke inhibits the colony of Colletotrichum sp. effectively.2. Mixture smokes S-822, S-824, S-829 and S-826 have inhibitory effects on the colony and conidium of Seirrhia acicola (Dearn.) Siggers,.3 . BHC is not only a insecticide, but can also control some forest diseases. It is notable that it is δ-BHC which plays the major part in killing fungi. BHC causes residue toxicity and environmental pollution, it. is necessary to develop a new fungicide smoke out of it.The smoke method has some advantages over spraying and dusting. The smoke can enter into very small crevices and other hardly accessible places, so it is preferable to apply it whenever a forest is infected by transmissive conidium.