[Objectives]  To provide additional scientific information for the management of Asian citrus psyllid (ACP) Diaphorina citri Kuwayama, the most important vector of the Huanglongbing (HLB) bacteria. [Methods]  The infection dynamics and distribution of HLB bacteria in different developmental stages of ACP were investigated using PCR, qRT-PCR and Fluorescence in situ hybridization (FISH). [Results]  HLB bacteria can be detected by normal PCR in 3^rd to 5^th instar nymphs and adults but can only be detected in 2^nd instar nymphs with qRT-PCR. The titer of HLB bacteria increased with nymph instar, and the titer of HLB bacteria in female adults in peak reproductive condition was significantly higher than that in pre-oviposition and post-oviposition females. In 4^th to 5^th instar nymphs, the distribution of HLB bacteria was scattered but mostly in the U-shaped bacteriome in the nymphs’ abdomen. The distribution of HLB bacteria in male and female adults was similar to that in nymphs, scattered rather than concentrated in the reproductive system. [Conclusion]  HLB bacteria infected 2-5 instar ACP nymphs and adults but its titer and distribution patterns varied among these different development stages.