The invention discloses a downlink service data processing method and device and user terminal. The method comprises the steps of receiving service data sent by a base station and carrying out a decoding operation on the service data, wherein the service data comprises TB (Transport Block) data composed of more than one piece of CB (Code Block) data; carrying out first checking on the decoded service data; sending a retransmission instruction to the base station when the first checking is unsuccessful and carrying out second checking on the CB data, thereby selecting the CB data which does not pass the second checking from the service data retransmitted by the base station, for the decoding operation. Through application of the method, the calculation quantity of carrying out the decoding operation by the UE can be effectively reduced.