Disclosed are a QR code detection device and an operation method thereof. The QR code detection device comprises a body, a barcode detector and a barcode decoder. The barcode detector captures and processes a code image outside the body, and accumulates a number of times when a predetermined pattern feature is recognized in the code image. The predetermined pattern feature is a predetermined distance ratio. The barcode detector chooses a near-distance detection rule or a far-distance detection rule according to the processed code image to determine whether the predetermined pattern feature is recognized in the QR code image. When the barcode decoder determines that the code image is a QR code image because the number of times equals to a threshold number, the barcode decoder is automatically turned on to capture and decode the QR code image outside the body.