embodiments of the present invention disclose a method for transmitting uplink ethernet data in a coaxial network , a coaxial network unit and a coaxial line terminal applying the method . in the method , the cnu determines a transmission path loss between the cnu and the clt , determines a transmission level for transmitting uplink data according to the transmission path loss , and transmits the uplink data by using the determined transmission level . the present invention ensures the security of data uplink transmission in an ethernet passive coaxial network system in essence and dramatically increases service quality .