The invention discloses a method and a device for ecological pond purification treatment of heavy metal-polluted irrigation water. The method comprises the following steps: step 1, selecting a place; step 2, constructing a tertiary ecological pond: performing capacity expansion, deepening, anti-seepage and partition treatment on an existing pond or low-lying land or abandoned land; step 3, constructing an absorption and purification pond: arranging a cement pond at the tail end of the tertiary ecological pond; step 4, putting absorbing materials: filling the materials for absorbing heavy metals at the bottom of the absorption and purification pond; step 5, in a primary ecological pond, planting aquatic plants; 6, in a secondary ecological pond, planting aquatic plants; step 7, in the tertiary ecological pond; planting aquatic plants and performing tertiary purification on the irrigation water. The device comprises the ecological ponds, the absorption and purification pond, a retaining wall, an ecological revetment, anti-seepage geotechnical cloth, a soil layer, a water inlet pipe, a water intake quantity regulating valve, the aquatic plants, the absorbing materials and a water outlet pipe. The device is wide in application scope, high in purification efficiency, simple in structure and easy to operate and manage and effectively reduces the treatment cost of the heavy metal-polluted irrigation water.