In order to study the vehicle roll and yaw stabilities of an articulated-mode truck，a model of articulated frame steer vehicle is established according to Adams/View on the basis of a 35-ton articulated frame steer mining truck，and a torsio-elastic suspension at the frontal and rear axles of the vehicle is installed． The kinematic and dynamic of hydraulic steering features were taken into consideration． In addition，a model of a hydraulic steering system was established in Matlab/Simulink． Then co-simulation between the Adams and Simulink for roll and yaw stabilities were analyzed． The validation of the Adams vehicle model was relayed on the vibration responses under the straight line maneuver，and hydraulic steering system validation was based on the response under the steady-turning and path-change maneuvers of vehicle． According to the roll and yaw stability measurement of articulated steer vehicles，the roll and yaw stabilities of unsuspended and suspended vehicles at unloaded and loaded conditions were also analyzed respectively． The results illustrated that the vehicle with torsio-elastic suspension will decrease the roll and directional stability，but the influence of the suspension system on the stability of articulated steer vehicles can be reduced through the suspension optimization