The invention relates to a four-degree-of-freedom posture leveling mechanism which comprises a movable platform, a fixed platform and four branch chains. The first branch chain comprises a ball pair, a first connecting rod, a first hook pair, a first driving block, a first moving pair and a first square column which are sequentially connected. Or the first branch chain comprises the ball pair, the first connecting rod, a first revolute pair, the first driving block, a cylinder pair and a cylinder which are sequentially connected. The second branch chain comprises a second hook pair, a second connecting rod, a second revolute pair, a second driving block, a second moving pair and a second square column which are sequentially connected. The first branch chain and the third branch chain are of the same structure and are arranged at opposite corners. The second branch chain and the fourth branch chain are of the same structure and are arranged at opposite corners. The four-degree-of-freedom posture leveling mechanism has the beneficial effects that the structure is simple, motion is simple comparatively, and control is concise comparatively; a novel machine type is provided for parallel motion equipment such as small-degree-of-freedom multi-dimensional vibration absorption, flight simulation, grabbing mechanisms, and the development and functionization of the parallel motion equipment are made possible.