The invention discloses a catheter and relates to the field of medical instruments. The catheter comprises a tube body, a closed airbag is arranged at an insertion part of the tube body, and communicated with an indication valve arranged outside the tube body through an air feeding tube; a side wall communicating tube which is communicated with tube body is arranged at a connecting part of the side wall of the tube body and a drainage pack; and a plug lid is arranged at the port of the side wall communicating tube. The catheter can solve the problems that the catheter damage is caused easily and nurse occupational injuries and workloads are increased to increase the cost and pain of a patient because the bladder pressure only can be measured after a syringe needle is required to puncture a tube cavity at the connecting part of the catheter and the drainage pack and then an infusion tube is connected when the patient needs to measure the bladder pressure during the indwelling period of the catheter.