<p>In the complex and uncertain project environment, an in-depth exploration of portfolio project risk management (PPRM) is of paramount importance. Effective PPRM can mitigate potential adverse impacts and maximize organizational value, driving sustainable development. However, current research mainly focuses on project portfolio (PP) returns, lacking comprehensive metrics that include non-financial value dimensions. There are also limitations in quantitatively assessing the relationship between risk management and value creation, requiring scenario simulations to better understand their dynamic interactions and complex dependencies. This study proposes a portfolio project risk (PPRs) assessment model guided by project portfolio value (PPVs). First, it identifies all system variables, including value dimensions and risk indicators. Then, using system dynamics (SD) methodology, a comprehensive value-oriented PPRs assessment model is constructed to quantify relationships between variables and explore the complex interactions under different scenarios. Ultimately, the model’s efficacy is validated through a highway project case study, with sensitivity analysis providing strategies to reduce PPRs and increase PPVs. The findings reveal the negative impact of PPRs on PPVs and its exacerbating effects, offering a new perspective for project portfolio practices and extending the theoretical and practical boundaries of risk management and value creation.</p>