The invention discloses an environment-friendly downhole stratum fracturing method, and belongs to the technical field of anti-reflection fracturing of horizontal wells, inclined shafts, vertical wells and the like. The method is achieved through an environment-friendly downhole stratum fracturing device. The environment-friendly downhole stratum fracturing device structurally comprises a well mouth plugging device, a downhole dragging device, well inside packers, a high-pressure hose, a well inside armor cable, a high-strength cable, an operating and control mechanism and a sensor assembly. Through the operating and control mechanism of the device, the downhole dragging device drags the two well inside packers to a set layer position, a set downhole stratum fracturing space is formed, the high-pressure hose is controlled to inject separation liquid, liquid powder, primary powder and the like into a to-be-fractured downhole space according to a formula proportion, the well inside cable is further controlled to carry out electronic ignition, high-energy and high-pressure gas stratum fracturing work is carried out, and multi-repeating or non-repeating stratum fracturing work of different stratum spaces and different stratum conditions is achieved. According to the method, the efficient, economical and environment-friendly stratum fracturing method and device are provided for coalbed methane / shale gas extraction, the fracturing effect is good, a large-range crack system is formed, the permeability of a reservoir stratum is improved, the desorption speed of the reservoir stratum is increased, and the aim of increasing production is achieved. The method and device are worthy of adoption and popularization.