[Objectives]  The citrus leaf miner, Phyllocnistis citrella, is an important pest of citrus. A simple and practical method was developed to sex adults and pupae of this pest quickly and accurately. [Methods]  The morphological characteristics of the abdominal segments of pupae and adults of citrus leaf miner were observed and compared. [Results]  In female pupae, the dividing line of the lower edge of the 7th ventral segment is not obvious, and the reproductive pore and anus are located in the 8th and 10th ventral segments, respectively. In male pupae, the dividing line of the lower edge of the 7th ventral segment is obvious, the reproductive pore is on the 9th ventral segment and the anus is on the 10th ventral segment. The end of the abdomen of adult females is cylindrical and, if pressed gently, black spots can be seen on both sides of the protruding end. However, in adult males, the end of the abdomen is tapered and covered with white scales. No black spots are apparent but there are a pair of long hair clusters which spread out when the end of a males’ abdomen is pressed. [Conclusion]  Adults and pupae of P. citrella can be sexed on the basis of morphological characteristics with 100% accuracy. These findings provide a reference for insect breeding technology, pest monitoring and the integrated control of the citrus leaf miner.