The present invention discloses a method for transmitting data. In the embodiments of the present invention, whether to send blocking information used to block low priority data sent by an upper layer is determined through monitoring a delay of data during transmission, so as to prevent data overflow in a retransmission buffer of the sending end, thus achieving higher INP protection for the low priority data. Meanwhile, only the low priority data is blocked at this time, therefore, a sending end may further continue receiving high priority data, and mark the high priority data with a flag indicating retransmission is not needed when encapsulating the high priority data, so that a receiving end does not apply for retransmission of the high priority data when receiving the high priority data, thus ensuring the short delay requirement of the high priority data.