Under standard condition(chamber pressure p_c : nozzle exit pressure p_e=70:1), the energy characteristic parameters of solid propellant containing 5-amino-tetrazolium nitrate (5-ATEZN), a novel kind of high energy compounds with high nitrogen content, were calculated by the least free energy method. Results show that specific impulse of 5-ATEZN monopropellant is 2371.38 N·s·kg^-1, which is similar to that of RDX and HMX monopropellant. Moreover, the oxygen balance of 5-ATEZN (-10.8%) is much higher than that of RDX and HMX. Specific impulse and characteristic velocity of HTPB propellant decrease with substituting 5-ATEZN for the ingredient AP or RDX. But for GAP propellant, specific impulse and characteristic velocity are characterized by a parabola with substituting 5-ATEZN for the ingredient AP. The maximum specific impulse can reach 2580.62 N·s·kg^-1, which is 17.93 N·s·kg^-1 higher than that of previous formula without 5-ATEZN. Since 5-ATEZN has no chlorine, it's helpful to reduce the characteristic signal of propellant. Therefore, substituting 5-ATEZN for the ingredient AP appropriately is a feasible approach to achieve the target of higher-energy and less-smoke for GAP propellant.