The characteristics of conventional triaxial creep are obtained via a conventional triaxial creep test of gascontaining coal under different stress levels. Mathematical fitting research regarding an experimental curve is done. A constitutive model of conventional triaxial creep of gascontaining coal is developed by improving a generalized KB model. The results show that the characteristics of conventional triaxial creep of gascontaining coal are related to the load step, and creep deformation is limited by the gas and confining pressures. Curves of the order 3ε(t) describe the three steps of conventional triaxial creep tests of gascontaining coal very well; the improved generalized KB model can represent a constitutive model of the conventional triaxial creep of gascontaining coal.