The utility model discloses a microseism exploder for an oil and gas well. The microseism exploder comprises an explosion delivering assembly, a female joint, a protective sleeve, an ignition head, a microseism sound source generator and a guider, wherein the lower end of the explosion delivering assembly is connected with the female joint; the microseism sound source generator is connected with the female joint through the ignition head, the ignition head is communicated with the explosion delivering assembly, one end of the protective sleeve is connected with the female joint, and the other end of the protective sleeve is connected with the guider; the ignition head and the microseism sound source generator are positioned in the protective sleeve, and an initiating explosive device is arranged in the microseism sound source generator. The microseism exploder disclosed by the utility model has the advantages that the application range is wide, and the explosion operation of high pressure (140 MPa) and deep well (7000 m) is met; meanwhile, an effective sound source is provided in explosion, a sleeve is not damaged after explosion, and no residue falls into a shaft.