To quantitatively understand impacts of climate and catchment property changes on land-surface hydrological processes in the Huai River Basin (HRB), China, can provide important information and theoretical basis for scientifically managing water resources in this region. We firstly evaluated the reliability of a new separation method to estimate contributions of climate (i.e., precipitation and potential evapotranspiration) and catchment property (i.e., Budyko parameter n) to changes in evapotranspiration (ET) and runoff (relative to the period of 1961-1980) in the HRB. Then, the estimated contributions of each factor by the new separation method were used to conduct the attribution analyses. Results showed that (1) both the qualitative and the quantitative validation measures indicated that the new separation method could efficiently and accurately estimate impacts of climate and parameter n on the ET and runoff changes. (2) Under the combined impacts of changes in climate and parameter n, both the reductions of ET and runoff were detected during 1980s and 1990s over the hydrological divisions (HDs) of Yi-Shu-Si River Basin (YSSRB). In the HDs of the upper (UHRB) and middle reaches (MHRB) of the HRB, the ET and runoff changes were characterized by evident decadal and spatial differences. (3) For the changed ET during each period, most of HDs corresponded to the dominants of parameter n, followed by precipitation and potential evapotranspiration (PET), which were respectively located in YSSRB and UHRB. In 1980s, the dominant factor of the changes in runoff over the HDs of MHRB was generally PET, while precipitation as the major contributor appeared in most of the remaining HDs. Most of HDs showed the dominant of the 1990s and 2000s runoff changes to be parameter n, followed by precipitation. To sum up, the physical mechanisms controlling changes in the ET and runoff over HRB existed obvious differences at space, and changed from period to period.