This application provides a data processing method and apparatus, and a computer storage medium. When a PDCP entity over a UM DRB is re-established, or when a cell handover occurs and the PDCP entity over a UM DRB uses a key used before the handover, the PDCP entity determines a first SDU, where the first SDU is an SDU that is associated with a sequence number by the PDCP entity but whose corresponding data has not been transmitted through an air interface; and delivers a PDU corresponding to the first SDU to an RLC entity. Data corresponding to the first SDU is redelivered, to avoid a data packet loss caused by preprocessing of the PDCP entity.