A crutch with a length controllable by pressure sensing and a method thereof are provided. The crutch includes a holding portion, a lead screw shaft, a rod body, a control module, and a supporting portion. The holding portion and the supporting portion have a plurality of pressure sensing units, for generating holding pressure values and feedback pressure values. The rod body is connected to the holding portion, a motor is arranged on the supporting portion, and the lead screw shaft has one end engaged to the motor and the other end pivoted to the rod body. When the holding portion determines that the holding portion is held according to the holding pressure values and the feedback pressure values, and that the crutch is oblique, the motor is enabled to rotate to drive the lead screw shaft to pivotally rotate, thereby shortening or prolonging the length of the crutch.