This paper examines experimentally the burning behaviors of transformer oil pool fires. A series of transformer oil pool fire tests with different pool diameters (0.2-1 m) were conducted. The mass burning rate, flame height, liquid layer temperature, flame temperature, and radiative heat flux were measured and analyzed. A new correlation for the mass burning rate as a function of pool diameter is deduced. The experimental flame height is compared to existing correlations, and it is found that the present result is in better agreement with those deduced for heavy oils. The liquid temperature results show that the fuel layer consists of a boiling layer and a gradient layer, and the thickness of the boiling layer is found to be around 2.6 mm independent of the pool diameter. The flame temperature is also analyzed and three zones are observed, for which a piecewise function is deduced. The radiation fraction and the emissive power of the flame are determined, respectively, based on the source flame model and solid flame model, and an exponential decay of the radiation fraction as a function of pool diameter is obtained. The present results are important for estimation of thermal radiation from a pool fire on the surrounding objects in practical transformer oil fires.