It is important to study the miniaturization of sun sensors used in the micro-nano satellites whose load requirement is rigorous. In order to solve the integration compatibility problem of optical devices and processing circuits, a novel on-chip sun sensor based on standard CMOS process is proposed in this paper. The micro-wall structure was constructed by metal layers, and the pn junctions were uniformly distributed on both sides as photoelectric sensors. The angle of incident light was calculated by detecting the ratio of photocurrents on both sides. The rationality and feasibility of the device were verified by the process realization, model establishment, numerical simulation and experimental testing in this paper. Finally, the on-chip sun sensor array chip is designed and fabricated whose mass is 1.5g, size is 304.2mm3, the detection accuracy is ±1.6° and the field of view range is 80°, which can meet the requirements of miniaturization.