Abstract: Due to the limitation of rocket fairings, deployable mesh antennas have to be folded compactly for launch and then deploy on orbit under zero-gravity conditions. On ground tests, however, the suspension system used to compensate the gravity cannot eliminate all of the effects of the gravity. This makes the ground tests fail to precisely predict the deployment behaviors in space. Therefore, it is in great demand to reveal and to understand the crucial differences of deployment dynamics between zero-gravity in space and gravity with a suspension system on ground through simulations. Based on the flexible multibody method, this paper presents full-scale multibody models of a state-of-art mesh antenna, Astromesh, for the cases of both zero-gravity and gravity. Using these models, the asynchronous deployment phenomenon was repeated, in which the bays of the antenna near the motor unfold faster than the bays far from it, as observed in the ground experiment. Besides, the driving force and the internal forces of all of the struts during the entire deployment process were systematically studied. Furthermore, the energetics was proposed to semi-analytically investigate the effect of gravity on the driving force. This study can support the structural and experimental design and optimization of the Astromesh. Moreover, the presented modeling method and the obtained results are helpful for understanding the deployment dynamics of other kinds of large mesh antennas.