Two-dimensional electron gases (2DEGs) at oxide interfaces possess many interesting physical properties. Particularly, when the time reversal symmetry is broken, they display a large unidirectional magnetoresistance, which is essential for exploiting two-terminal devices based on such a nonreciprocal response. Here we report a nonreciprocal charge transport behavior in conductive 2DEG at the LaAlO3/KTaO3 interface, and the nonreciprocal coefficient $\gamma $ of up to $\sim {6}.{8}\times {10} ^{\text {-10}}\text{A}^{-{1}}\text{T}^{-{1}}$ cm2 is obtained. Remarkably, the nonreciprocal response is highly tunable by applying gate voltages in a field-effect device. Our work illustrates that KTaO3-based 2DEG is an outstanding platform for the development of multifunctional two-terminal devices and may pave a route for future gate voltage tunable rectification devices.