A data transmission method, applied to a terminal, the terminal being a wireless terminal, the method comprising: when receiving, by an Access Stratum, AS, of the terminal, first data borne on a first AS Bearer, ASB, converting, by the terminal, the first data into a first Internet Protocol, IP, data packet of a first IP flow according to mapping relationships between IP flows and ASBs; sending, by the terminal, the first IP data packet to a Non-Access Stratum, NAS, of the terminal; and characterized in that the method further comprises: when the AS of the terminal receives a second IP data packet of a second IP flow sent by the NAS of the terminal, bearing, by the AS of the terminal, the second IP data packet on a second ASB according to the mapping relationships between the IP flows and the ASBs and then sending, by the AS of the terminal, the second IP data packet out, wherein the method further comprises: caching, by the terminal, the second IP data packet in the AS; when receiving a retransmission request for the second IP data packet, resending, by the terminal, the second IP data packet cached in the AS; and when receiving feedback information indicating successful reception of the second IP data packet, deleting, by the terminal, the second IP data packet cached in the AS. when receiving, by an Access Stratum, AS, of the terminal, first data borne on a first AS Bearer, ASB, converting, by the terminal, the first data into a first Internet Protocol, IP, data packet of a first IP flow according to mapping relationships between IP flows and ASBs; sending, by the terminal, the first IP data packet to a Non-Access Stratum, NAS, of the terminal; and characterized in that the method further comprises: when the AS of the terminal receives a second IP data packet of a second IP flow sent by the NAS of the terminal, bearing, by the AS of the terminal, the second IP data packet on a second ASB according to the mapping relationships between the IP flows and the ASBs and then sending, by the AS of the terminal, the second IP data packet out, wherein the method further comprises: caching, by the terminal, the second IP data packet in the AS; when receiving a retransmission request for the second IP data packet, resending, by the terminal, the second IP data packet cached in the AS; and when receiving feedback information indicating successful reception of the second IP data packet, deleting, by the terminal, the second IP data packet cached in the AS. when the AS of the terminal receives a second IP data packet of a second IP flow sent by the NAS of the terminal, bearing, by the AS of the terminal, the second IP data packet on a second ASB according to the mapping relationships between the IP flows and the ASBs and then sending, by the AS of the terminal, the second IP data packet out, wherein the method further comprises: caching, by the terminal, the second IP data packet in the AS; when receiving a retransmission request for the second IP data packet, resending, by the terminal, the second IP data packet cached in the AS; and when receiving feedback information indicating successful reception of the second IP data packet, deleting, by the terminal, the second IP data packet cached in the AS. caching, by the terminal, the second IP data packet in the AS; when receiving a retransmission request for the second IP data packet, resending, by the terminal, the second IP data packet cached in the AS; and when receiving feedback information indicating successful reception of the second IP data packet, deleting, by the terminal, the second IP data packet cached in the AS.