Due to intense human activities, urban street dusts and river sediments are usually polluted by heavy metals. This study investigated the seasonal variations (summer and winter) of pollution level, spatial distribution and potential sources of heavy metals in street dusts (SD) and river sediments (RS) of Dongluo River watershed, Ji’nan, China. Results showed cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) contents were 3.5 (8.6), 3.0 (1.4), 4.9 (2.6), 4.1 (1.1) and 3.9 (4.0)-fold of their geochemical soil background values (BGV) of Shandong Province, China in summer (winter). Mercury (Hg) and arsenic (As) contents were lower than their background values in both summer and winter. The differences of Cd, Cr, Cu, Pb, Zn, Mn and As contents in river sediments between winter and summer were not statistically significant. The correlation coefficients between metal contents and the distance between sampling sites and the east-west boundary of study area were higher in summer than those in winter. Based on principal component analysis (PCA) and multivariate linear regression (MLR), coal combustion and traffic-related sources were the main sources in winter, and agricultural activities and traffic-related sources were the main sources in summer.