Provided are a writing trajectory processing method, a touch control device, a writing system and a storage medium. The writing trajectory processing method includes: obtaining writing data of an original writing trajectory, wherein the writing data comprise a plurality of first trajectory points and a plurality of first contact areas corresponding to the plurality of first trajectory points one to one; smoothing the writing data to obtain smoothed writing data; wherein the smoothed writing data comprise a plurality of second trajectory points and a plurality of second contact areas corresponding to the plurality of second trajectory points one to one; determining a plurality of trajectory line widths corresponding to the plurality of second trajectory points one to one based on the plurality of second contact areas; and, displaying the writing trajectory based on the plurality of second trajectory points and the plurality of trajectory line widths.