The invention discloses a drilling and pressure releasing device and a drilling and pressure releasing device method for a long-time shutting well. The drilling and pressure releasing device for the long-time shutting well is used for being arranged outside a pressure-building casing pipe of the long-time shutting well, and comprises a casing pipe strengthening clip clamped outside a casing coupling, a pipeline and a spraying pipe, wherein the whole casing pipe strengthening clip is annular, and an opening hole is formed in the side wall of the casing pipe strengthening clip; one end of the pipelines is matched with the opening hole position of the casing pipe strengthening clip and communicates with the opening hole; a gate is arranged at the other end of the pipeline; a draining outlet is formed in the pipeline; a blocking part which can fall off under predetermined pressure is arranged on the draining outlet; the spray pipe is arranged in the pipeline in a penetrating manner and isused for allowing drilling fluid with the predetermined pressure to flow through; a spray nozzle is arranged at one end of the spray pipe and is just opposite to the opening hole. According to the drilling and pressure releasing device and the drilling and pressure releasing method for the long-time shutting well, provided by the invention, efficient and safe pressure release can be realized.