The present invention relates to the technical field of communications. Provided are a method and system for reducing power consumption of a mobile terminal, and mobile terminal. The method comprises: detecting network performance of a mobile terminal communication module comprising a first communication module and a second communication module; if the network performance of the first communication module is better than that of the second communication module, then causing the first communication module to remain turned on, and turning off the second communication module; and controlling, according to a network resource allocation of the first communication module, turning on of the second communication module. The present invention can turn off the second communication module when a network resource of the first communication module satisfies a data service downloading requirement, and turn on the second communication module for downloading when the network resource of the first communication module does not satisfy the data service downloading requirement, thereby reducing power consumption of the mobile terminal while satisfying the data service downloading requirement thereof.