The invention discloses a manufacturing method of a GaN-based transistor with high electron mobility based on a TiN/Cu/Ni gate electrode, and mainly solves the problem that existing similar components are high in cost. The manufacturing process comprises the following steps: manufacturing a source electrode, a drain electrode and an active area on an epitaxial substrate for electrical isolation, and growing an SiN passivation layer; photoetching and etching a gate groove area on the SiN passivation layer; photoetching gate electrode areas on a gate groove and the SiN passivation layer, using a magnetron sputtering technology to sedimentate a TiN Schottky contact layer, a Cu conducting layer and an Ni protective layer in sequence, and forming a gate electrode of a TiN/Cu/Ni structure after peeling; growing SiN protective layers on the gate electrode and the SiN passivation layer; photoetching and etching a metal interconnection opening area on the SiN protective layers; and manufacturing metal interconnecting layers on the interconnection opening area and the SiN protective layer so as to complete device manufacturing. The manufacturing cost of the gate electrode is reduced, the reliability of the transistor is improved, and the transistor can be used for manufacturing high-frequency high-power integration modules.