Abstract:Based on the data obtained by single watershed experiment, the changes in streamflow by forest fire were studied. The results showed the forest fire in Daxinganling in 1987 resulted in the increase of annual runoff obviously in the initial stage,the runoff of melting snow in May tended to reduce. After forest fire, the ability to regulate the water circulation of forest was reduced, and the changes in streamflow depended on the precipitation even more.