[Objective] The study of river ecological water demand in the southern mountain area of Jinan City, Shandong Province based on ecohydrological variation characteristics was carried out to provide theoretical basis for regional water resources integrated management and ecological protection, strengthening ecological protection, and promoting sustainable development of the Yellow River basin. [Methods] The runoff data from Gushan station (Beidasha River) and Wohushan station (Yufu River) in the southern mountainous area of Jinan, located in the lower reaches of the Yellow River, were collected for the period 1979 to 2021. The study utilized the cumulative anomaly method, Mann-Kendall (M-K) test method, sliding T-test method, and double accumulation curve method to analyse abrupt changes in runoff. The IHA-RVA method was additionally used to examine variations in river runoff and ecological water demand. By comparing the rivers’ satisfaction with ecological water demand, this paper investigated key factors influencing the regional ecohydrology and variations in ecological water demand while proposing protective measures to ensure adequate supply within the study area. [Results] The runoff mutation points of Beidasha River and Yufu River were observed in 1996, and the overall hydrological alteration degrees were determined to be 72.75% and 69.42%, respectively, indicating significant alterations in both rivers. The annual ecological water demand of Beidasha River and Yufu River was 1.47×10⁶ m³ and 1.81×10⁶ m³, respectively. Overall, the monthly ecological water demand satisfaction of the Beidasha River and Yufu River was 32.35% and 60.42% on average, respectively. [Conclusion] The hydrological variation in the southern mountainous area of Jinan was found to be large before and after the mutation, and the overall satisfaction of the ecological water demand was relatively low. The ecological water demand of rivers may be guaranteed by strengthening the ecological regulation of rivers and improving the efficiency of water resource utilisation.