The invention provides a system for detecting the characteristic value of a note and a method for detecting the characteristic value of the note. The system includes a fixing panel which includes a first detection window; a moving panel which includes a sampling block and a second detection window, wherein the sampling block and the second detection window move along with the moving of the moving panel; a detection apparatus which is intended for, when it is determined that the sampling block moves to the position corresponding to the first detection window along with the moving of the moving panel, detecting the testing value of the sampling block, based on the testing value, and computing a light source modification coefficient, and when it is determined that the second detection window moves to the position corresponding to the first detection window along with the moving of the moving panel, based on the initial characteristic value of the note, acquiring the transmission speed of the note being transmitted to the first detection window, and based on the initial characteristic value, the transmission speed and the light source modification coefficient, determining the final characteristic value of the note. According to the technical solution of the invention, the system and the method effectively increase the accuracy in detecting the characteristic value of the note.