The Huizhou 26 sub-sag is rich in oil and gas resources,but its fluid phases are complex and variable, with unknown origins. Based on crude oil properties, well fluid compositions, and organic geochemical data, this study applies empirical statistical methods and PVT phase diagrams to identify the hydrocarbon phase types in the area. The spatial distribution characteristics and genetic mechanisms of these phases are analyzed. Through a comprehensive examination of the formation stages and processes of different reservoir types , three phase evolution models are proposed:initial oil-phase filling, two-stage oil-phase superposition, and early oil-phase followed by late gas-phase charging. The results provide theoretical guidance for the efficient exploration of deep hydrocarbons. The crude oil from Huizhou 26 sub-sag is characterized by low density, low viscosity, low sulfur content, and high wax content. Three hydrocarbon phase types are identified:black oil, volatile oil, and condensate gas. Among these, black oil is the most widely distributed, while volatile oil and condensate gas occur mainly in the Huizhou 26-6 and 21-8 structural zones. Vertically, the Enping Formation is dominated by volatile oil and condensate gas, whereas black oil, volatile oil, and condensate gas coexist in the Wenchang Formation. Some wells display vertical alternation of oil and gas phases. The spatial variability of oil and gas phases is primarily controlled by the thermal maturity of source rocks and the hydrocarbon charging process. Specifically, the maturity level of hydrocarbons during the main filling stage and the extent of late mixing with high-maturity hydrocarbons are the key controlling factors.