The purpose of the study was to investigate the effect of oxygen concentration on pool fire combustion in specific locations where oxygen concentrations exceed 21% due to oxygen leaks, such as rocket launch sites, aircraft, submarines, etc. The combustion characteristics of small-scale pool fires under high oxygen concentrations should be conducted by experimental and theoretical analysis. This study discussed the effects of high oxygen concentrations on heat release rate, burning rate, and combustion efficiency under Fire Propagation Apparatus (FPA) test conditions and measured the flame height and boiling mechanisms in a Semi-open Oxygen-adjustable Experimental Platform (SOEP). The results show that boiling combustion of small-scale pool fires is more intense, the burning rate and heat release rate in the boiling stage are significantly enhanced under high oxygen concentrations. Empirical models of flame height and heat feedback have been established. In conclusion, the hazards of oxygen-enriched fires were evaluated. This study provides foundational data and predictive models to mitigate the threats posed by oxygen-enriched pool fires in the process industry.