A novel single color camera trichromatic mask 3D-PIV technique suitable for measurement of complex flow fields in confined spaces is presented in this paper. By using a trichromatic mask to modulate the imaging optical path of a color camera, the RGB (Red, Green, and Blue) channels of the photosensitive chip were used to record full-frame full-resolution images of tracer particles from three viewing angles. The MLOS-SMART particle reconstruction algorithm was used to obtain three-dimensional particle distribution matrix from particle trichromatic mask images. The impact of parameters such as the inter-hole spacing and hole diameter of the trichromatic mask on the quality of particle reconstruction was analyzed. Through numerical simulation experiments on artificially synthesized three-dimensional flow fields of Gaussian vortex rings, the practicality of this technique in measuring three-dimensional transient velocity fields and the accuracy of velocity measurements were examined. The accuracy and feasibility of the technique are illustrated based on experimental measurements of a zero-net-mass-flux jet.