Abstract: A vehicle body inclination angle regulating unit (17) includes a balancing oil cylinder (10). One chamber of the balancing oil cylinder (10) is connected with an oil tank (5) and an oil source for leveling operation via a first one-way damper valve (8) and an electric controlled switch valve (7), and the other chamber of the balancing oil cylinder (10) is connected with a non-rod chamber of a suspension oil cylinder via an electric controlled shutoff valve (14) and a second one-way damper valve (9). In addition, an automatically-leveling hydropneumatic suspension mechanism includes at least two pairs of suspension oil cylinders (12), vehicle body inclination angle regulating units (17), a vehicle body transverse inclination angle sensor (1) and a control unit (3). Each suspension oil cylinder (12) is correspondingly provided with the vehicle body inclination angle regulating unit (17) including the balancing oil cylinder (10).