In order to study the effect of shape and size on the molecular tailoring process of single-base propellant， three gradiently denitrated single-base propellants （seven-holes， one-hole and non-hole single-base propellants） were prepared by using hydrazine hydrate as denitration agent. Based on the Avrami model， the kinetics of the molecular tailoring process of different shapes of single-base gun propellants has been investigated. The results showed that the Avrami model could be used to describe the molecular tailoring process of three single-base propellants. The Avrami index n of seven-holes propellant was greater than 1 when the reaction temperature was in the range of 70-75 ℃， which was controlled by the chemical reaction process. When the temperature was in the range of 75-80 ℃， n<1， it was controlled by a combination of internal diffusion and chemical reaction. The Avrami index n<1 for one-hole and non-hole single-base propellants， and the molecular tailoring process was controlled by a combination of internal diffusion and chemical reaction. According to Fick"s law， the diffusion coefficient D of one-hole single-base propellants was 3.8×10^-13-10.2×10^-13 m²·s^-1， and that of non-hole single-base propellants was 3.7×10^-13~5.1×10^-13 m²·s^-1. Using the Arrhenius equation， the apparent activation energies of the seven-holes， single-hole and non-hole single-base propellants were calculated to be 45.84， 52.88 and 38.26 kJ·mol^-1， respectively. The study of the kinetics of molecular tailoring reaction for different shapes of single-base propellants can provide theoretical guidance for the controllable preparation of gradiently denitrated single-base propellants.