Embodiments of the present application belong to the field of NB-IoT, and relate to a method, terminal and server for allocating NB-IoT system resources, capable of satisfying the requirements of traffic rate and communication quality simultaneously. The method comprises the following steps of: acquiring a traffic request of a first terminal; determining bearing carriers and the number of the bearing carriers required for bearing downlink data of the first terminal based on candidate carriers information and downlink traffic rate requirement; determining target downlink transmitting power of each of the bearing carriers based on the reception quality information, the determined bearing carriers, the determined number of the bearing carriers and the reception strength information; and determining to transmit the downlink data of the first terminal on an i-th bearing carrier using the determined target downlink transmitting power if a total downlink transmitting power of the i-th bearing carrier is less than or equal to a first preset threshold.