The invention discloses a semi-trailer with a fire extinguishing apparatus. The semi-trailer with the fire extinguishing apparatus comprises a trailer body, a carbon dioxide storage tank, a water tank, a firefighting water delivery pipe reel, a water delivery pipe, a gas delivery pipe, a telescopic rod, a thermal imager, a display, a tire cooling and fire protection device and a controller; the water tank and the carbon dioxide storage tank are arranged at the bottom of the trailer body of the semi-trailer; the gas delivery pipe is mounted in a gas outlet of the carbon dioxide storage tank; the gas delivery pipe is positioned at the front end of the trailer body and perpendicular to the upper surface of the trailer body; the firefighting water delivery pipe reel is arranged on the side wall of the trailer body; the water delivery pipe is wound on a wheel spoke; one end of the water delivery pipe is clamped on a telescopic bracket; the other end of the water delivery pipe is connected with an input pipeline on the wheel spoke; the other end of the input pipeline is connected to the water tank; the thermal imager is also arranged on the telescopic bracket; and the tire cooling and fire protection device is arranged under the trailer body. According to the semi-trailer with the fire extinguishing apparatus, fire disasters of trains can be effectively prevented and fire can be extinguished in time to reduce loss to the utmost extent.