Electromagnetic radiation signals from computer displays can be a computer security risk if the radiation signal is intercepted and reconstructed. In addition to the information displayed by the computer, electromagnetic radiation leaks the information of the computer itself which is more important for some attackers, protectors and security inspection workers. In this paper, we demonstrate that electromagnetic radiation signals of computer LCD vary considerably between different devices and analyzed the reason by checking main circuits of computer LCD. Furthermore, this paper proposes the concept of the emanation fingerprint and uses high-order cumulants to extract the features of computer LCD emanations to construct the emanation fingerprint. The proposed fingerprint algorithm (EF algorithm) can realize the individual recognition of computer LCDs automatically and accurately without reconstruction of the display image.