In order to improve the measurement accuracy and efficiency of the single-shot structured light measurement system, the phase unwrapping algorithm of the most important step in the three-dimensional reconstruction of structured light was improved. A phase unwrapping algorithm based on multiple pigeonholes adaptive sorting was proposed, which efficiently suppressed the error transmission during the unwrapping process and significantly improved the calculation efficiency. Firstly, the unreliability function of a pixel was defined according to the second-order difference of the pixels, and adjacent pixels were combined into a pixel group. Secondly, the pigeonholes with different ranges of unreliability values was constructed adaptively to meet the requirements of error transmission, and then pixel groups were placed into the pigeonholes with corresponding parameters in turn. Finally, the phase unwrapping was performed in ascending order according to the unreliability value of the pigeonholes. The verification experiments were carried out in a monocular structured light system. The experimental results show that the phase unwrapping algorithm proposed improves the efficiency by 38.37% compared with the original algorithm, and the accuracy of the point cloud solution has been greatly improved. It effectively optimizes the relevant performance of the measurement system.