The embodiment of the invention discloses a method and device for determining oil and gas reserves and a water body scale. The method comprises the steps of obtaining a fluid property parameter; determining a storage type of a target area; determining a first mapping relationship according to the fluid property parameter and the storage type of the target area, and determining crude oil reserves and first water body volume according to the first mapping relationship; or determining a second mapping relationship according to the fluid property parameter and the storage type of the target area, and determining natural gas reserves and second water body volume according to the second mapping relationship. According to the method and device for determining the oil and gas reserves and the water body scale provided by the embodiment of the invention, the oil and gas reserves and the water body scale of a carbonate fracture-vug type carbonate rock oil and gas reservoir can be calculated quantitatively.