Based on Boltzmann transport equation and Landauer equation, characteristics of the thermoelectric parameters such as the figure of merit, electrical conductance and power factor for two kinds of modulus were studied, including a constant and a Gauss-typed distribution functions with a finite energy spectrum width. Compared with Delta-typed modulus, it is found that the figure of merit decreases but the electrical conductance and the power factor increases after the spectrum width is introduced. The thermoelectric performance of the two kinds of modulus is more practically meaningful than that of the Delta-typed modulus.