Urban waterbody morphology design plays a crucial role in enhancing the visual appeal of urban waterscapes, and the quantitative characterization of its morphological features offers valuable data support for waterbody design. Accurately quantifying these features and applying them to parametric design is of significant importance for urban waterscape development. This study presents a waterbody morphology index system containing eleven key indicators, and constructs a parametric design model based on Grasshopper, which links parametric regulation with morphology analysis to integrate design, analysis, and optimization within a single platform. The method was applied to 42 typical waterbody cases in China, establishing the indicator thresholds for urban waterbody morphology. The parametric model was further applied and tested in Suqian City Park. After pre-analysing the current site conditions to determine site selection and initial morphology, six waterbody morphology design scenarios were selected, quantified, and analysed with the support of the parametric model and indicators data, with targeted morphological regulation to optimize the design. This case demonstrates the model's potential for real-time analysis and iterative design refinement. The research emphasizes the importance of parametric design in transforming complex morphological features into quantifiable design drivers, providing methodological insights for the interpretable and adjustable morphological design of urban waterbodies.