A trench semiconductor device and a method of making the same are provided. The trench semiconductor device includes a trench MOS device and a trench ESD protection device. The trench ESD protection device is electrically connected between the gate electrode and source electrode of the trench MOS device so as to provide ESD protection. The fabrication of the ESD protection device is integrated into the process of the trench MOS device, and therefore no extra mask is required to define the doped regions of the trench ESD protection device. Consequently, the trench semiconductor device is advantageous for its simplified manufacturing process and low cost.