The invention discloses a data processing method. The method comprises the following steps of: when UE receives a message indicating that new downstream data arrives, starting an RTT timer of a receiving end; after the RTT timer of the receiving end is overtime, starting a retransmission timer of the receiving end; and after the retransmission timer of the receiving end is overtime, if the decoding of the downstream data fails, starting the RTT timer of the receiving end. The embodiment of the invention also discloses a data processing system. Through setting a starting condition and a stopping condition for each timer, the embodiment can solve the problem of data transmission failure caused by the loss of a PDCCH message so as to improve the transmission performance.