The invention discloses a long-acting self-locking packer and a use method thereof. The long-acting self-locking packer includes a central tube, a pressure transmitting hole, an upper joint, a lower joint, an unsealing mechanism, a locking mechanism, a control ring, a fixed structure, an oil filling setting mechanism, and a cylinder sleeve, wherein the pressure transmitting hole is formed in the central tube, a boss is also arranged on the outer circle of the central tube, the upper joint and the lower joint are connected to the upper and lower ends of the central tube respectively, the upperpart of the unsealing mechanism is fixedly connected to the upper joint; the locking mechanism is connected to the lower part of the unsealing mechanism, the control ring is arranged between the unsealing mechanism and the upper joint; the upper end of the fixed structure is connected with the lower end of the locking mechanism, and a cavity is formed between the central tube and the fixed structure, the lower end of the locking mechanism is located in the cavity, and the cavity communicates with the pressure transmitting hole; the upper part of the oil filling setting mechanism is arranged atthe lower part of the cavity, the lower end part of the oil filling setting mechanism is fixedly connected to the fixed structure, the cylinder sleeve is connected to the lower end of the oil fillingsetting mechanism, and an oil filling opening communicating with the oil filling setting mechanism is formed in the cylinder sleeve. According to the long-acting self-locking packer and the use method thereof, damage of the packer does not affect the sealing performance of a separate injection pipe column, and the packer can automatically expand and seal to prevent interlayer communication.