The invention discloses a system for utilizing rainwater to irrigate a potted plant. The system comprises a rainwater receiver, a water storage tank, a filter, a pipeline, the potted plant, a rain sensor, a sliding ring, pulling rods, a motor and a vertical rod. The system is characterized in that the lower end of the rainwater receiver is fixedly connected with the upper end of the water storagetank, and an opening of the rainwater receiver faces upwards; the bottom of the water storage tank is fixedly connected with the end, away from the sliding ring, of the vertical rod; the filter is fixedly connected with the water storage tank; the filter and the potted plant are fixedly connected to the two ends of the pipeline respectively; the rain sensor is fixedly mounted on the upper portionof the end, close to the sliding ring, of the vertical rod; the sliding ring can slide up and down on the surface of the vertical rod; the sliding ring is hinged to one end of each pulling rod, and the rain receiver is fixedly connected to the other end of each pulling rod; the motor is mounted in an inner cavity of the interior of the lower end of the vertical rod. The system can automatically sense rainy days and open the rainwater receiver to collect rainwater, so that the space occupancy rate is decreased, and meanwhile impurities in the rainwater are filtered out; the filtered rainwater is directly transported to the potted plant, so that water of water resources is reduced, and meanwhile labor burden on people is reduced. The system is simple in structure, reliable in function, low in cost and suitable for mass industrial production.