Previous single-MHD simulations demonstrate that ballooning instability can develop in thin-current sheet configurations of near-Earth magnetotail, which would in turn induce plasmoid formation and three-dimensional magnetic reconnection in absence of inward solar wind flow from magnetopause [1,2]. Our recent two-fluid MHD simulations find that such a mechanism for plasmoid formation in magnetotail remains viable in regimes and scales where Hall and finite-Larmor-radius (FLR) effects become no longer negligible. Both linear and nonlinear calculations are carried out to evaluate the two-fluid effects on the ballooning instability and its consequence, based on a generalized Harris sheet configuration of the magnetotail. Whereas FLR effects reduce and stabilize linear growth of ballooning instability at ion gyroradius scale, Hall effects can significantly increase the number of plasmoids formed along the Earth and tail-ward direction after the nonlinear growth of ballooning instability. The emergence and presence of multiple plasmoids induced by nonlinear ballooning instability suggests a potential origin of the series of neighbouring magnetic islands in magnetotail observed during a substorm expansion phase [3]. References [1] P. Zhu and J. Raeder, Phys. Rev. Lett. 110, 235005 (2013). [2] P. Zhu and J. Raeder, J. Geophys. Res. Space Physics 119, 131-141 (2014). [3] L.-J. Chen et al, Phys. Plasmas 16, 056501 (2009).