In this study, four types of training systems for Citrus grandis var. longanyou, natural round shape, double-layered shape, open center shape, and Y-shape, were used, and structural characteristics of the different canopies and structural and physiological characteristics of the leaves were compared for a better understanding of the canopy microclimate and correlation with canopy growth to provide guidance and support for orchard production practices such as pruning, watering, and fertilizing. The results showed that:(1) The gap fraction threshold of open center shape was the highest, which was 4.33 times of the natural round shape. Photosynthetically active radiation (PAR) and transmission coefficient of the open center shape and Y-shape systems were significantly higher than those of the other two training systems, which indicates that the capabilities of the open center shape and Y-shape systems to intercept and distribute light in the canopy were better than those of the other two systems. (2) Parameters such as Leaf thickness (LT), Stomata density (SD), Leaf area (LA), Thickness rate of palisade and sponge tissue (PTT/STT), and Organizational structure closely degrees (CTR) measured for the open center shape and Y-shape systems were higher than those of the other two systems, which indicates that the leaves of the former two systems show improved photosynthesis and reduced transpiration. (3) Parameters such as Net photosynthetic rate (Pn), Water use efficiency (WUE), Max apparent electron transport rate (ETR max), Initial slope (α), and Half-saturation light intensity (I_k) measured for the open center shape and Y-shape were higher, which indicates that these two training systems have better tolerance to strong light. However, Transpiration rate (Tr=2.43 mmol m^-2 s^-1) and the photoinhibition parameters (β=0.629) of the bearing branches were minimum for the open center shape system, which is the best system to photosynthetic efficiency. (4) The measured parameters' correlativity between canopy microclimate and structural and physiological characteristics of the leaves was highly significant, but the correlation for the open center shape system was lower than that of the other systems. This indicates that the leaves of the vegetative and bearing branches show the lowest differences in the whole canopy of the open center shape system and that the open center shape is the best training system for light interception and distribution in the canopy.