The utility model discloses a casing gas pressurizing recovery device of an oil well. The casing gas pressurizing recovery device comprises a machine seat, a driving device, a compressor and a casing gas path, wherein a driving wheel of the driving device is provided with a ratchet mechanism, a spiral spring is arranged between the driving wheel and a driving wheel shaft, the driving wheel and the compressor are connected by the driving wheel shaft, a compressor pipeline is connected with the casing gas path, the driving wheel is driven by a driving rope which is wound on the driving wheel, the natural gas compressor is driven to work by a belt and a speed adjusting wheel, and gas in the casing is sucked, pressurized and conveyed into an oil well pipeline. The casing gas pressurizing recovery device has the advantages that the certain suction capability is realized, the casing gas can be effectively recovered and reutilized, the resource is saved, the casing gas is reasonably controlled, the production level of the oil well is improved, and the normal production is guaranteed.