The invention discloses a capsule endoscope for examining esophageal diseases. The capsule endoscope comprises a capsule shell, an imaging device, a control device, an air bag, an inflation / deflation device connected with the air bag, and a pressure sensor, wherein the air bag is transparent and arranged on the periphery of the capsule shell, the inflation / deflation device and the pressure sensor are both arranged in the capsule shell, the inflation / deflation device is used for driving the air bag to be opened or contracted, and the pressure sensor is used for measuring the pressure of air in the air bag. According to the capsule endoscope, the size of the air bag can be controlled through the inflation / deflation device according to the pressure or peristalsis force of the esophagus wall, so that sufficient contact between the air bag and the esophagus wall is achieved, the moving speed of capsules is reduced, the esophagus is stretched, and then the image or video of the esophagus wall can be acquired easily and the lesion part of the esophagus wall can be treated.