The invention provides a method and a device for realizing the one-number multiple-card technology, a home location register and a communication system. The method comprises steps that, a user group including at least two user terminals is distributed with a user identification number; call identification numbers are distributed to each user terminal in the user group; when the user identification number is called, at least one user terminal in the user group is called according to the call identification number. Through the method, the one-number multiple-card technology is realized, multiple user terminals can commonly use one user identification number, use cost of the users is reduced, the quantity of user identification numbers distributed by a service provider is reduced, management and maintenance cost of the service provider are further reduced, and a problem of high cost existing in the one-number one-card technology in the prior art is solved.