MaizeField3D is a 3D point cloud dataset of maize plants, designed to address the lack of large-scale and diverse data for AI-based 3D phenotyping research. High-quality 3D point clouds of 1,045 field-grown maize plants were collected using a terrestrial laser scanner (TLS), and 520 of them were individually segmented and annotated into leaves and stems using a graph-based segmentation method. The labeled data are used for procedural modeling to provide a structural parameter representation of maize plants, with leaves represented as NURBS surfaces. The dataset contains metadata on plant morphology and quality, as well as subsampled point cloud data at various resolutions (100k, 50k, and 10k points), and has undergone rigorous manual quality control. MaizeField3D can be used as a foundation dataset for AI-based phenotyping, plant structure analysis, and 3D applications in agricultural research.