Errors can occur in the 2D projection contact angle measurements of droplets on uneven material surfaces, and currently, only a few international equipment manufacturers offer 3D contact angle measurement solutions. This paper proposes a 3D droplet contact angle measurement method aimed at providing a complete and practical 3D contact angle measurement solution. The system employs an array of circular structured light for 3D detection, suitable for liquids with contact angles less than 90° and good diffuse reflection properties.The main steps include: feature region selection, 3D point cloud acquisition, droplet surface fitting, and contact angle measurement. In the image preprocessing stage, a method based on HSV space combined with morphological operations is proposed. For feature region selection, an area filtering method is introduced. Geometric calculations are used to convert 2D point clouds to 3D point clouds, and a point cloud matching algorithm is proposed to optimize point cloud fusion.Compared to 2D measurement methods, experimental results show that the proposed method significantly improves measurement accuracy and reliability, achieving a maximum error of less than 1°, with most errors being less than 0.5°. Additionally, it allows for further analysis of material physical properties and surface uniformity.