The invention discloses an automatic detecting device for a large-array resistance strain gauge. The automatic detecting device comprises a frame, a positioning and fixing mechanism, a detecting mechanism, a computer, a data acquisition board, a table digital multimeter, and an output amplification board. The positioning and fixing mechanism comprises a two-dimension mobile platform, a vacuum adsorption table, and a vacuum adsorption loop. The vacuum adsorption table comprises an adsorption table lower cover and an adsorption table upper cover. The vacuum adsorption loop comprises a vacuum pump, a vacuum filter, a vacuum degree regulating valve and a vacuum solenoid valve. The detecting mechanism comprises a first cylinder sliding table, a cylinder sliding table installation plate, a second cylinder sliding table, a pneumatic loop, a probe box, a detecting circuit board, and a spring probe array. The pneumatic loop comprises an air pump, an air filter, a reducing valve, and a pressure gauge. The invention further discloses an automatic detecting method for the large-array resistance strain gauge. The automatic detecting device is novel and reasonable in design, low in production cost, high in operation reliability, reduces worker labor intensity and product production cost, and achieves high popularization and application value.