Chair with variable centre of gravity

The invention relates to a chair with a variable centre of gravity. The chair with the variable centre of gravity is characterized in that a backrest is hinged with a seat, rear chair legs are hinged with the backrest, draw bars are hinged with the rear chair legs, the seat is hinged with the draw bars to form a four-bar mechanism, a rear trolley is installed on the tail end of each rear chair leg, and the variation of the angle of the four-bar mechanism is controlled by an angle adjusting mechanism. When the angle adjusting mechanism stays at a locking state, the four-bar mechanism is held still, and the angle between the backrest and the seat is constant; when the angle adjusting mechanism stays at a free state, the four-bar mechanism can move freely under the effect of external force to drive the rear trolleys to roll back and forth, and the distance between the front chair legs and the rear chair legs is greater when the angle between the backrest and the seat is larger; the distance between the front chair legs and the rear chair legs is smaller when the angle between the backrest and the seat is smaller, and the centre of gravity is changed along the variation of elevation.