The granular jet can behave macroscopically like a liquid jet and its dispersion process is similar to the break-up of the liquid jet by an annular air jet. In this paper, the particle dispersion characteristics of a granular jet by an annular air jet, such as the undisturbed length, the dispersion length and the dispersion angle, have been investigated experimentally with a high-speed camera. The results showed that the air jet velocity and granular jet mass flux are the main influencing factors on the undisturbed length and dispersion length of the granular jet. The particle diameter has few effects on the undisturbed length and dispersion length of the granular jet. The empirical equations of the undisturbed length, dispersion length and dispersion angle are obtained. (c) 2012 Elsevier B.V. All rights reserved.