The scale effect plays an important role in the hydrological responses to environmental change, which has been testified in many studies.However, the effect of temporal and spatial scale on hydrological change is not sufficiently studied.In this paper, a case study of such effect on the streamflow trend in Jialing River Basin is carried out.It is assumed that if the effect of spatial scale on the results of hydrological change does exist, it will escalate from the upper reach of the river to the lower reach.