Abstract: In order to study the structural evolution and thermodynamic properties of the first wall material tungsten (W) in electronic excited state during irradiation, the physical properties of W in fusion reactors were studied theoretically by using tight-binding potential model. It is found that the electronic excitation induced by the irradiation of energetic particles leads to the events such as spontaneous appearance of micro-voids, sharp expansion of the lattice, and decrease in the melting point of the irradiated regions in W. Specifically, the lattice expansion of W is mainly driven by lattice temperature under the medium temperatures (~5 000 K). But the lattice expansion effect caused by electronic temperature cannot be ignored at the higher temperatures. Especially when the electronic temperature is rather high (>10 000 K), the electronic temperature will cause a large degree of lattice expansion, even if the lattice temperature is low for the irradiated regions. These findings bring benefit to gain deep understanding in the physical performance of W in fusion reactors during service.