The embodiment of the invention discloses a method and system of dispatching a MCS (Modulation and Coding Scheme) in an HARQ-ACK/NACK (Hybrid Automatic Repeat reQuest-ACKnowledgement)/(Negative ACKnowledgement) binding mode. The method comprises the following steps: calculating temporary adjustment amount of an outer-ring MCS according to HARQ feedback information; updating an outer-ring MCS value according to the temporary adjustment amount of the outer-ring MCS; and dispatching a current MCS value according to the outer-ring MCS value. The technical scheme of the invention solves a problem that the MCS value is reduced excessively because a base station misjudges the actual NACK number of the HARQ feedback information, and increases a downlink service transmission rate while guaranteeing the downlink service transmission reliability of the base station.