The invention relates to the technical field of display, provides a thin film transistor, a display substrate and a display device and aims to solve the problem of bad disconnection of follow-up electrodes in via holes. The thin film transistor comprises an active layer, a gate insulator, a grid electrode, an interlevel dielectric, a source electrode and a drain electrode, and the active layer, the gate insulator, the grid electrode, the interlevel dielectric, the source electrode and the drain electrode are sequentially arranged on a substrate. The source electrode and the drain electrode are respectively connected with the active layer through via holes exposed outside the active layer; the grid insulator at least comprises two silicon oxide layers and two silicon nitride layers, and the interlevel dielectric at least comprises four silicon oxide layers and four silicon nitride layers; all silicon oxide layers and silicon nitride layers of the gate insulator and the interlevel dielectric are arranged at intervals, and one side, away from the substrate, of each via hole is larger than one side, close to the substrate, of each via hole. The thin film transistor is applicable to manufacturing of the display device and the display substrate with the thin film transistor.