The invention provides an expanding type differential pressure opening type fine leakage finding and leakage checking packer. The expanding type differential pressure opening type fine leakage finding and leakage checking packer comprises an upper rubber sleeve and a lower rubber sleeve, wherein two ends of the upper rubber sleeve are connected with an upper rubber sleeve upper base and an upper rubber sleeve lower base respectively; the two ends of the lower rubber sleeve are connected with a lower rubber sleeve upper base and a lower rubber sleeve lower base respectively; the upper rubber sleeve lower base and the lower rubber sleeve upper base are connected though a check valve body, and the check valve body is provided with a check valve; and an upper slit central pipe is arranged in the upper rubber sleeve, and a lower slit central pipe is arranged in the lower rubber sleeve. By adopting a manner of combining the upper and lower rubber sleeves and the check valve, the aims of accurately determining a layer position, finely judging a leakage point position and easily unpacking setting are realized according to low-differential-pressure setting and a constant distance of the upper and lower rubber sleeves and a high-differential-pressure forward opening function of the check valve; and the problems of an existing old well leakage finding and leakage checking packer (tubular column) of an existing oil-gas well that leakage finding is extensive, a leakage point is easy to miss, performances are not reliable, the unpacking is difficult and the like are solved.