Assessing the roll maneuvering stability of tailless fighters is of paramount importance, as stability constrains the maximum roll rate, which is a crucial metric for evaluating aircraft maneuverability. However, due to the predominance of nonlinearity and coupling in the flight dynamics of tailless fighters, conventional methods based on simplified models are not sufficiently accurate. This paper employs an Extended Bifurcation Analysis (EBA) approach to investigate the stability of roll maneuvers of tailless fighters by zero-sideslip constraint, and employs time-domain simulation to identify characteristic unstable modes. The results indicate that the roll maneuvering of these tailless fighters exhibits stability loss and abrupt transitions, leading to an onset of a wing rock motion. Unlike traditional configurations, the maximum roll rate of tailless fighter aircraft is limited by deflection of elevator rather than ailerons. The theoretically maximum roll rate is approximately 80  \(^\circ \) C per second, which is lower than that of fighters with conventional configuration, suggesting an inferior maneuverability.