With the assumption of local Tsallis equilibrium, the newly defined gravitational temperature is calculated in the solar interior, whose distribution curve can be divided into three parts, the solar core region, radiation region and convection region, in excellent agreement with the solar hierarchical structure. By generalizing the Fourier's law, one new mechanism of heat conduction, based on the gradient of the gravitational temperature, is introduced into the astrophysical system. This mechanism is related to the self-gravity of such self-gravitating system whose characteristic scale is large enough. It perhaps plays an important role in the astrophysical system which, in the solar interior, leads to the heat accumulation at the bottom of the convection layer and then motivates the convection motion.Keywords: Gravitational temperature; heat conduction; convection motion. PACS: 44.10.+i; 51.20.+d; 96.60.Jw.As everyone knows, almost all the physical systems treated in statistical mechanics with the Boltzmann-Gibbs (BG) entropy are extensive and this property holds for the systems with short-range interactions. However, when dealing with the systems with long-range interactions such as Newtonian gravitational forces and Coulomb electric forces, the BG statistics may need to be generalized for their statistical description.In recent years, nonextensive statistics mechanics (NSM) based on Tsallis entropy [1] has been proposed as a generalization of BG statistics. This new statistics theory has been used to deal with many interesting problems in the systems with long-range interactions, among which the self-gravitating system is one important research field [2-6]. The theoretic and observational successes for the NSM in this field show that, possibly this statistics theory is one fundamentally valid method to describe the astrophysical system. Combining the Newtonian mechanics or general relativity, it can be used to interpret various phenomena in astrophysics.On the other hand, it is difficult for the scientists to carry out the thermodynamic research on the astrophysical system. The ordinary results they could obtain in their researches are the gravothermal catastrophe [7,8] and the negative thermal capacity [7]. These results prevent people from getting more insight into the essence of the gravity in the view of thermodynamics. Although with the NSM these results can be avoided partly [9], it is very difficult to formally introduce the heat conduction mechanism, in the astrophysical sense, into the self-gravitating system. The main reason for this is that, in the development process of the NSM, the controversy on the temperature definition holds back the emergence of the thermodynamics in the framework of the NSM.