River sediments are widely regarded as essential archives for source-to-sink system analysis and paleogeographic reconstruction, yet their provenance signals may be substantially altered during downstream transport due to tributary dilution and heterogeneous zircon yield. Traditional provenance studies have frequently overlooked these factors, which may result in biased interpretations. In the Songhua River Basin, the mechanisms through which tributary inputs influence detrital zircon age variations in the mainstream, along with the quantitative evaluation of their sedimentary contributions, have yet to be fully clarified. In this study, detrital zircon U-Pb geochronology was conducted on sediments from the Songhua River mainstream and its major tributaries, including the Nenjiang, Jilin Songhua, and Lalin Rivers. By integrating a dilution index, zircon yield correction, and inverse Monte Carlo model, it explores the source-to-sink system of the Songhua River Basin. The detrital zircon age spectra are defined by four principal age populations: 202～110 Ma, 523～205 Ma, 2066～1564 Ma, and 2747～2341 Ma. Both tributary dilution and differences in zircon yield exert substantial control on zircon age distributions. The effects of tributary dilution gradually diminish with increasing transport distance, whereas zircon-yield correction effectively mitigates biases arising from variations in zircon fertility among source rocks. Two recommendations for provenance studies are proposed: (1) sampling sites should avoid river confluence zones and preferably be located at least 50～100 km downstream from confluences; and (2) zircon-yield correction ought to be prioritized to enhance the accuracy of provenance assessment. Zircon reproducibility tests demonstrate the absence of ~1800 Ma ages in detrital zircon records from the Jilin Songhua River, suggesting that reliance solely on age peaks is insufficient to fully capture regional magmatic-tectonic events. By integrating tributary dilution and zircon-yield controls and combining detrital and igneous zircon datasets, this study addresses the limitations of single-indicator provenance methods and establishes a more robust framework for sediment provenance tracing and paleogeographic reconstruction in the Songhua River Basin.