The utility model relates to a medical product technical field especially relates to a tourniquet. Tourniquet is including the area body, be provided with circuit board, comparison circuit module andthe alarm that has first electric conductor and second electric conductor on the body of area, first electric conductor and second electric conductor are connected with the input electricity of comparison circuit module respectively, and the output electricity of comparison circuit module is connected with the alarm, the part or whole of first electric conductor, the part or whole of second electric conductor are exposed in the surface of the area body, the conducting resistance value has been predetermine to the comparison circuit module to a when the resistance value reached the conducting resistance value, the comparison circuit module switched on the alarm for $monitoring between first electric conductor and the second electric conductor. the utility model provides a tourniquet to it results in hemorrhage back patient to find untimely technical problem to solve the tourniquet aversion that exists among the prior art.