Abstract: The interaction of light with matter can induce a variety of optical phenomena, amongst which photovoltage is one of the most important. In this paper we report our experimental and theoretical studies on perovskite oxide heterojunctions which exhibit traditional vertical photovoltage as well as unusual lateral photovoltage . The dynamic process of the photovoltaic effect in perovskite oxide heterojunctions is analyzed and explained by means of a self\\consistent calculation based on the drift-diffusion mode. We first describe our experimental and theoretical results for the vertical photovoltage effect, followed by those for the lateral photovoltage. Finally, their potential applications are discussed.