A chair structure comprising: a base , configured to be a chair base assembly; a seat support , which is located above the base , wherein the front part of the seat support has rotary connection with the front part of the base through a transition link ; a chair back assembly, which has rotary connection with the rear part of the base through a pivot ; a lever driving member , which is linked between the chair back assembly and the seat support ; the lever driving member has rotary connection with the rear part of the seat support ; said lever driving member and the seat support are approximately on the same surface; when the chair back assembly rotates rearward around the pivot from the initial position, the rear part of the seat support is raised diagonally to the rear through the lever driving member , meanwhile the transition link and the front part of the seat support are pulled up; characterized in that said chair back assembly consists of a connecting member and a bracket , wherein said connecting member has rotary connection with the rear part of the base through the pivot , and said bracket comprises an upper supporting frame of a back and side supporting frames which are extending downward along the left and right side of the upper supporting frame of the back ; the lever driving member comprises two lever driving members, and the two lever driving members are of lateral symmetry and formed by extending forward from a middle and lower part of the side supporting frame ; lower ends of both side supporting frames meet in the middle and extend forward to connect to the connecting member ; said seat support comprises two bilaterally symmetrical supporting bars , wherein rear parts of the two supporting bars have rotary connection with the two lever driving members respectively, and front parts of the two supporting bars are connected as a whole through a cross bar ; the lever driving member and the supporting bar are approximately connected in a straight line. a base , configured to be a chair base assembly; a seat support , which is located above the base , wherein the front part of the seat support has rotary connection with the front part of the base through a transition link ; a chair back assembly, which has rotary connection with the rear part of the base through a pivot ; a lever driving member , which is linked between the chair back assembly and the seat support ; the lever driving member has rotary connection with the rear part of the seat support ; said lever driving member and the seat support are approximately on the same surface; when the chair back assembly rotates rearward around the pivot from the initial position, the rear part of the seat support is raised diagonally to the rear through the lever driving member , meanwhile the transition link and the front part of the seat support are pulled up; characterized in that said chair back assembly consists of a connecting member and a bracket , wherein said connecting member has rotary connection with the rear part of the base through the pivot , and said bracket comprises an upper supporting frame of a back and side supporting frames which are extending downward along the left and right side of the upper supporting frame of the back ; the lever driving member comprises two lever driving members, and the two lever driving members are of lateral symmetry and formed by extending forward from a middle and lower part of the side supporting frame ; lower ends of both side supporting frames meet in the middle and extend forward to connect to the connecting member ; said seat support comprises two bilaterally symmetrical supporting bars , wherein rear parts of the two supporting bars have rotary connection with the two lever driving members respectively, and front parts of the two supporting bars are connected as a whole through a cross bar ; the lever driving member and the supporting bar are approximately connected in a straight line. <EOS>