The invention discloses a QR two-dimension bar code automatic recognize method based on chat camera, which can quickly and effectively recognize the QR two-dimension bar code read by general chat camera. The invention is not limited in special two-dimension bar code recognizer, to expand the limit condition of input bar code. For the QR bar code image under natural light, the invention designs a self-adaptive threshold division algorism to binary treat the bar code image. When accurately positioning four tops of the QR bar code, based on the character of a position detect image in the QR code, finds three tops, and when positioning the fourth top, using a digging algorism to dig the QR bar code image, to avoid the interference of internal points in Hough conversation, and for resolving the defects of traditional Hough conversation as large calculation and high spatial complexity, the invention designs a Hough conversation crossing known points. Based on the character that the QR code image is square in distortion, the invention uses control point conversation to correct geometry distortion, and uses dual-linear interpolation in gray interpolation in the conversation.