The invention relates to a novel positioning evaluation anti-counterflow device for a laboratory rat oral trachea cannula. The novel positioning evaluation anti-counterflow device comprises the cannula, an adapter, a tee joint, an air guide tube, a switch and a bubble barrel. The cannula is connected with the front end of the adapter, the rear end of the adapter is connected with a first port of the tee joint, a second port of the tee joint is connected with a respirator, the front end of the air guide tube is connected with a third port of the tee joint, and the rear end of the air guide tube is communicated with the bubble barrel. An airflow channel with the round cross section and the trapezoidal longitudinal section is formed in the bubble barrel, the port, with the small hole diameter, of the airflow channel is communicated with the air guide tube, the port, with the large hole diameter, of the airflow channel serves as a bubble outlet, and the switch is installed on the air guide tube. It can be guaranteed that the trachea cannula is located in the trachea lumen of a rat and kept smooth, bubbles escaped from the bubble barrel in the expiration period of the rat are easy to observe, and liquid can be prevented from counterflow from the bubble barrel and the air guide tube in the inspiration period of the rat.