A chair chassis, comprising a chassis pedestal, a left and a right connecting rod for back, a seat supporting frame, an adjusting handle, the adjusting handle comprises an adjusting screw rod. On the adjusting screw rod exists a locating block for mounting handle and, the first pulling line and the second pulling line are wrapped around it, the two pulling lines are respectively used to lock or unlock the tilting angle of the back and to lock or unlock the position of the supporting frame; the adjusting handle also comprises a block for the pulling line, which is connected with the third pulling line, and the block for the pulling line is connected with the adjusting screw rod and can relatively slide on it. The invention is multi-functioned with the action of only one adjusting handle, and the structure of the invention is compact, and it is convenient to operate.