This paper presents a new mathematical model of the heat transfer characteristics for oil shale particles during the retorting. In this process, the heat transfer within oil shale particles affects shale oil yield and energy consumption. To explore the heat transfer characteristics of oil shale particles in more detail, experiments on its thermal conductivity were conducted to confirm that oil shale was an anisotropic material. The results showed that the thermal conductivity in the parallel direction was about 1.25 times higher than that in the perpendicular direction. The dimensions of crushed oil shale particles were measured, and the ratios of length to width, length to thickness and width to thickness showed that the oil shale particles had a clear platy structure. Based on the experimental results, a new mathematical model, which considered the pyrolytic heat as an internal heat sink, was developed. It was validated that the model could be used to predict the central temperature history and heating time of oil shale particles during the retorting. Furthermore, the central temperature history and heating time of oil shale particles with different sizes were predicted, assuming oil shale to be either an isotropic or anisotropic material. The results showed that when oil shale was regarded as an isotropic material, there was a relatively marked disagreement between experimental and actual results. In addition, the relationship between the heating time and oil shale particle equivalent diameter was established.