Since 1980s, with the increasing impacts of human activities on the river basin landscape, it is significant to investigate the impact of landscape changes on the rainfall-runoff regime. This paper simulated the floods occurred in the Zijingguan and Fuping catchments of the Haihe Basin using an empirical method. The flood data were segmented by time for creating the P+P_a~R_s curve to analyse the influence of the altered catchment landscapes on surface flow regime. Based on the unit hydrograph method, the relationship between the runoff R and peak discharge Q_m was established. The results show that by comparison of the trendlines in different time periods, with the same runoff volume, the peak discharge after 1980s is less than that before 1980s. It indicates that the water regulation function of Haihe Basin was enhanced. Based on the relationship between the changes of runoff and peak discharge induced by the altered basin landscapes, it is found that there is a positive correlation between them.