Generalized information domain is the space of all digital information that can be expressed by binary code. In this paper, a random number generator based on discrete trajectory transform in generalized information domain is proposed. The generator exploits generalized information domain as the space of entropy source, and uses the digital information selected by the user as the output of entropy source, and then utilizes the discrete trajectory transform method to generate random number based on the reconstruction of the output of entropy source. The proposed generator shows good characteristics of balance, period and anti-collision, and it demonstrates satisfactory randomness through the National Institute of Standards and Technology test. This generator can be utilized to generate high secure random number quickly and conveniently.