A data communication method includes: a Radio Network Controller (RNC) sends a notification message to a Node B to instruct the Node B to perform proper operations after a specific event occurs on the User Equipment (UE). A data communication system, a data sending apparatus and a data receiving apparatus are also provided in an embodiment of the present disclosure. Through the technical solution under the present disclosure, when specific events such as cell handover, disconnection and state transition occur on the UE, the RNC that obtains the event information may send a notification message to Node B to instruct the Node B to perform proper operations. Therefore, the Node B is prevented from continuing to send the buffered UE data from the source cell; and in the Cell_FACH state, the present disclosure saves the radio channel resources, shortens the transmission delay, and reduces the transmission packet loss ratio.