The two-dimensional semiconducting materials with tunable electronic structure and high thermoelectric properties have a wide range of applications, especially in nanoscale devices. This study uses the Kubo-Greenwood formula in the framework of the Green function approach and the tight binding model to calculate the thermoelectric properties of trilayer SiC (3L-SiC). 3L-SiC is a semiconductor that can transform to metallic state with increasing applying the external fields with critical strength. The thermoelectric properties of the 3L-SiC and 3L-BN were analyzed under bias voltage, magnetic field and temperature up to 1500 K and compared with each other. The results show that thermal properties of the 3L-SiC are higher than that 3L-BN and both structures exhibit strong dependence on bias voltage and magnetic field with higher sensitivity to the magnetic field. The thermal properties of the selected structures increases with temperature and the external fields enhance the increasing rate. The behavior of the Lorenz Number in terms of temperature exhibits general pattern as increasing from zero to maximum value at TM and decreasing by further temperature increasing.