The invention discloses an automatic rainstorm runoff sampling and monitoring device and an automatic rainstorm runoff sampling method. The automatic rainstorm runoff sampling and monitoring device comprises a base, a power supply, and a rainfall collector, a flow monitor, a signal transceiving and data storage device and a water sample collecting, sealing and storing integrated device which are mounted on the base and connected with the power supply, and a sampling bottle turnplate system connected to the upper side of the water sample collecting, sealing and storing integrated device. Through use of the automatic rainstorm runoff sampling and monitoring device, automatic collection, monitoring and storage of a runoff water sample in the field can be achieved. Through the automatic watersample collecting, sealing and storing integrated device, the sealing and storage problems of the water sample are solved; through the rainfall monitor and the flow monitor, device opening is achievedon the basis of the rain intensity, and during collection and monitoring, the function of collecting more rainwater at a large flow, collecting less rainwater at a small flow is achieved; through a water quality monitoring probe, the function of monitoring physical indexes of the water quality while the water sample is collected is achieved.