Abstract: Pegmatite is widely developed in the Baoban complex in the western part of the Hainan Island. However, the fluid inclusion types and fluid characteristics of the pegmatite are not well understood, which limits research on its genesis within the Baoban complex. Based on the study of geological characteristics of the pegmatite, this paper carried out the petrographic observation, microthermomentric analyses and laser Raman spectral composition analysis. The fluid inclusions in the pegmatite can be classified into four types based on their composition: CO₂-H₂O inclusion (type I), biphase H₂O inclusion (type II), CO₂ inclusion (type III) and monophase liquid H₂O inclusion (type IV). The total homogenization temperature of type I inclusions in quartz ranges from 290.7 ℃ to 406.7 ℃ (mean = 344.5 ℃), and the salinity ranges from 1.6 % to 9.2 % (mean = 5.8 %). The total homogenization temperature and salinity of type II inclusions in quartz and quartz core range from 191.2 ℃ to 403.2 ℃ (mean = 265.6 ℃), 190.2℃ to 304.2℃ (mean = 225.9℃), and 0.4 % to 6.5% (mean = 3.09 %), 0.2% to 6.6% (mean = 1.98%), respectively. Laser Raman spectroscopy revealed that the primary gas-phase components of type I inclusions are CO₂, with a small amount of CH₄, while the gas-phase and liquid-phase components of type II inclusions are both H₂O. The fluid of pegmatite in the Baoban complex in the Hainan Island characterizes with low-medium temperature, low salinity and low density, indicating the fluid has undergone boiling. The pegmatite in the Baoban complex formed through the magmatic crystallization and differentiation of a deep magmatic chamber, with no genetic relationship with the Mesoproterozoic gneissic granite.