The invention discloses a layered waterstop method and device outside a casing pipe for a layered underground water pumping test. Water swelling rubber containing sodium polyacrylate super absorbent resin is used as a waterstop material outside the casting pipe for the test, and the waterstop time and swelling ratio of water swelling of the water swelling rubber are controlled by controlling the proportion of the sodium polyacrylate super absorbent resin added into the water swelling rubber according to the time of the water pumping test, so that the waterstop time for completing seam sealingis adjusted. According to the layered waterstop method and device outside the casing pipe for the layered underground water pumping test, the water swelling waterstop time of the water swelling rubbercan be adjusted within 12 hours to 7 days, and the water swelling rubber is high in tensile strength and tenacity, can withstand an underwater pressure over 20Mpa and is particularly suitable for layered underwater pumping tests under complex geological conditions, high construction difficulty and large depths; the layered waterstop method and device have the technical effects of accurate and reliable layered sealing waterstop effect, longer layered waterstop, and convenient control; and meanwhile, the test efficiency and the accuracy of test data are greatly improved.