The invention discloses a data coupler based on a coaxial cable hybrid transmission technology. Because the prior device adopts a lithium ion battery for power supply, the reliability is poor, the efficiency is low and the maintenance cost is high. The data coupler comprises a low-pass filter module and a high-pass filter module; one end of the low-pass filter module is connected with a power supply module, one end of the high-pass filter module is connected with a modulating and demodulating unit, and the other ends of the two filter modules are respectively connected with a coaxial cable. The low-pass filter module comprises two differential-mode capacitors, two common mode capacitors and a common mode inductor. The high-pass filter module comprises three coupling capacitors and a bidirectional transient voltage suppressor. The data coupler fully utilizes the characteristics of the designed low-pass filter which presents low impedance to the direct current signal, and presents high impedance to the high-frequency signal, so as to realize hybrid transmission of the data of the power energy and image information through the coaxial cable, therefore, the structure of the subsea device is simplified, and the production cost and the maintenance cost are reduced.