The thermal conduction, thermal expansion, and dynamic thermomechanical behaviors of gel-cast SiAlON green bodies during thermal debinding were systematically studied using thermal analysis methods. The evolution of the thermophysical properties of the green body was revealed. The results showed that residual moisture had a great impact on the deformation of the green body during debinding and may even be greater than the deformation caused by the gel pyrolysis process (2.8% residual moisture). Under the current test conditions, the maximum linear expansion coefficient of the green body was 1.85 × 10−5 °C−1, the thermal diffusivity ranged from 0.21 to 0.46 mm2·s−1, and the specific heat ranged from 0.37 to 0.55 J·(g·K)−1. The storage modulus curve exhibited bimodal distribution with two peak intervals, and the range of values was 35–47 MPa. These results can provide the key thermophysical parameters for the study of the stress and strain behaviors of green bodies during thermal debinding. [ABSTRACT FROM AUTHOR]