Digital displacement radial piston pump offers an alternative to existing drivetrain concepts of wind turbines. However, today's hydraulic components have not been scaled up to handle the loads of multi-megawatt turbines. This study aimed to exploit the mechanical design of digital-displacement radial piston pump for large-scale wind turbine drivetrain with the combination of parametric modeling, algorithm-based generative design and simulation-based evaluation methods. It first presents the analysis of working principles, parametrical modeling of major components and mathematical modeling of design constraints of the pump. Then, an exhaustive method-based generative approach is proposed for more innovative and effective pump design and the mechanical-hydraulic coupling model is developed for dynamic characteristic analysis and design evaluation. The proposed models and approaches are then applied to the design of a 5 MW radial piston digital-displacement pump for demonstration and validation. The comparison between the proposed optimal pump design scheme and an existing conceptual pump shows similar efficiency, but much more compact structure, higher power density and potentially better controllability and reliability which are likely preferred for wind turbine application. (C) 2019 Published by Elsevier Ltd.