Rubber tree is the most important cultivated rubber-producing plant, and the tapping of trunk is the only way to obtain natural rubber from the laticifer in the bark currently. The characteristics of latex flow after tapping determine the latex yield, but the mechanism of latex flow is not yet completely clear. The turgor pressure of bark is the main initial driving force for latex flow, and the content of lignin, as the main component of cell wall, is closely related to the turgor pressure. At present, the study on the lignin content in bark of rubber tree is deficiency, among which the analysis of lignin content by morphological structure is lack. Using the bark of RY8-79 and PR107 mature tree as the research materials, paraffin sections were prepared, and the lignin in the bark was stained and localized by Wiesner reaction, Mäule reaction, and safranin staining combined with fluorescence, respectively. The results showed that both Wiesner reaction and Mäule reaction could stain the lignin component of the parenchyma cell wall, but difficult to distinguish different strains and tissues for the light color. The light purplish red of lignin in the parenchyma cell could be observed after safranin staining, but it was also difficult to distinguish different tissues and strains. The obvious red fluorescence of lignin tissue could be observed after safranin staining combined with 546 nm green light excitation, and there was significant difference among different cell types and strains. The lignin fluorescence of parenchyma cell in RY8-79 was significantly weaker than that in PR107, indicating that the content of lignin in RY8-79 was lower than that in PR107. Iodine-bromine staining showed that the distribution of secondary laticifer was consistent with the distribution of lignin with strong fluorescence, indicating that the lignin content of secondary laticifer and its surrounding parenchyma cells increased significantly, especially in PR107. In addition, Wiesner and Mäule reaction needed dangerous chemical reagents such as phloroglucinol, hydrochloric acid and potassium permanganate (KMnO₄), respectively, and the reaction time was not easy to control for slices falling off from slides and cell wall damage. By comparison, the reagents used for safranin staining combined with fluorescence observation were safe and non-toxic, and the structure of cell in bark could maintain intact easily. According to the comprehensive analysis of different methods, for the excellent clarity of lignin as well as safety and simplicity of operation, safranin staining combined with fluorescence observation is the most suitable method for lignin location in parenchyma cell of rubber tree bark.