A piezotronic pulsed GaN-based photoconductive TeraHertz (THz) emitter is proposed and simulated for the first time. In this paper, we benefit from high break down-voltage, thermal conductivity, and saturation velocity of GaN, to design a pulsed antenna-less THz emitter. The proposed emitter consists of asymmetric metal-semiconductor-metal structure. Moreover, strong coupling of semiconducting/piezoelectric properties in GaN, allows modulation of the dissimilar Schottky barriers, leading to tunable THz output power and bandwidth. Our simulation results demonstrate that applying an external strain of about 4% results in 26% enhancement in the radiated THz power, while output bandwidth is improved about 4.2%. The proposed structure is promising for emerging reconfigurable THz emitters, capable of being tunable by external strain as a controlling gate.