Structure-improved multifunction chassis

A structure-improved multifunction chassis includes a chassis base, a handle and a plurality of pull lines, wherein the chassis base includes a backrest angle adjustment device, a cushion height adjustment device, and a cushion back-and-forth moving device. The chassis base is pivotally connected with a left and right connecting rod of a seat backrest frame. The handle includes a shift arm, a handle fixed block, and a handle base. The handle fixing block is installed in the handle base and is able to swing up and down. The handle fixing block is mounted on the handle base by bolts. One handle controls three pull lines at the same time, and the user adjusts the angle of the backrest, cushion lifting or moving back and forth by operating the handle.