The invention aims to provide an automatic precipitation sampler which comprises a sampling bottle, a sampling bottle sensor, a pressure sensor, a detection funnel, a rain collection funnel, a cover, a rotary motor, a lifting rod, a lifting rod motor and a water injection mechanism, wherein the lifting rod is mounted below the cover; the lifting rod motor drives the lifting rod so that the cover moves up and down; the rotary motor is connected with the cover and drives the cover to rotate; the cover covers the rain collection funnel; the rain collection funnel is communicated with the water injection mechanism; the sampling bottle is arranged by corresponding to the water injection mechanism; the sampling bottle sensor is mounted on the water injection mechanism to detect whether the sampling bottle is full of water or not; the detection funnel is arranged beside the rain collection funnel; a pipeline blocking rainwater is connected below the detection funnel; a bypass pipe is mounted on the pipeline; and the pressure sensor is mounted on the bypass pipe. The automatic precipitation sampler provided by the invention can automatically collect rainwater in precipitation and automatically stop sampling after the rain stops; and after the collection, the precipitation automatic sampler can store the sample perfectly and record the precipitation-related data.