An insight to the nonextensive parameter in the actual gas

► We deduce the relation between the nonextensive parameter and the second virial coefficient. ► The coefficient is the integration of interaction potential of the gas molecules. ► This verifies that the nonextensive parameter is related to the interaction of molecules. ► The nonextensive parameter is irrelevant to the thermodynamic temperature of the gas. ► In quantum statistics, the deviation of a parameter from unity may be very small.