Most of the small rivers in the Shandong Peninsula have clear sediment sources and relatively small mineral deposition differentiation, and their study can provide regional similarities for the analysis of the sources of large rivers into the sea, as well as the characteristics of the material sources in the Shandong Peninsula for the deposition of the Yellow Sea shelf and Bohai Sea shelf. In this paper, the distribution patterns of detrital minerals in surface sediment samples taken from riverbeds, estuaries and beaches were analysed at multiple grain levels, taking the Xin’an River, a small short-source river in the northeastern part of the Shandong Peninsula, as an example. The study shows that the Xin’an River basin and beach sediments are mostly medium and fine sands, with moderate heavy mineral content in the whole sample, ranging from 1.47% to 8.19%. Twenty-seven heavy minerals and eight light minerals occur, with the main heavy minerals hornblende (41.7%), chlorite (16.7%), actinolite (10.6%) and limonite (6.7%) and the main light minerals quartz (49.0%), plagioclase (26.5%) and potassium feldspar (20.7%), which are much more abundant than the other detrital minerals in the riverbed, estuary and beach, and the mineral assemblage remains constant, with less significant variation in relative content between them, while there is a significant non-linear correlation between non-dominant mineral species and clastic grain size. Mineral species and content in the Xin’an River are controlled by the regional lithological sources, i.e. acidic and moderately acidic intrusive rocks and regional metamorphic rocks, and the relatively stable output of amphibole group minerals across the different features of the Xin’an River is responsible for their homogeneity. The short source rivers of the Shandong Peninsula are derived from similar geological features and rock types, although the types and content of detrital minerals vary. The main controlling factors for mineral composition variation are regional sources and particle size sorting, followed by sedimentary environmental differences. In contrast, the high content of mica group and carbonate minerals in a specific grain size and the low content of amphibole group minerals are the aspects that distinguish the Huanghe River from the river source materials in the northern and southern coastal waters of the Shandong Peninsula.