In the context of global warming，it is of great significance to clarify the change characteristics and trends of hydrological elements in the mountainous areas of inland river basins to ensure water resource security. In this study，the spatiotemporal variation of hydrological elements under four scenarios，SSP1-2. 6，SSP2-4. 5， SSP3-7. 0 and SSP5-8. 5，was predicted with the SWAT model and the collective average data of five global cli‐ mate models in CMIP6. The results showed that：（1）The evaluation coefficient of the SWAT model was higher in the calibration period（NSE=0. 92，R2=0. 93，PBIAS=-7. 09%）and validation period（NSE=0. 89，R2=0. 91， PBIAS=4. 74%），indicating that SWAT had good applicability in the simulation of runoff in the upper reaches of the Heihe River Basin.（2）Under the four scenarios，the runoff from the mountains in the future will increase by 12. 2%，8. 1%，10. 4% and 19. 2% respectively compared with the base period，and the runoff will increase significantly in autumn and winter. In the near and far future，the increase in the average total water yield in the basin is between 6. 2~25. 4 mm（22. 2~35. 7 mm），and the increase in the average underground flow is 1. 6~7. 4 mm （7. 4~12. 1 mm），and the increase of each hydrological element is greater in the far future.（3）In terms of the spatial distribution of hydrological elements，the spatial distribution of precipitation，evapotranspiration，surface production and underground runoff increased from northwest to southeast，while the total water yield and lateral flow were high in the middle and low in the north.（4）The spatial distribution pattern of the changes of each hydrological element is quite different，and the spatial distribution difference of the change of hydrological elements between different scenarios in the near future（2021-2060）period is relatively small，and the difference in the temporal and spatial distribution of the change in the far future（2061-2100）is even greater. In conclusion，the SWAT model can better describe the temporal and spatial changes of hydrological processes and hydro‐ logical elements in the mountainous areas of inland river basins.