The invention relates to repeated bending testing equipment under constant load and a method, belonging to the field of detection technique. The equipment comprises a drawing system and a bending system, wherein the drawing system is provided with a second clamping device connected with an elastic device and a drawing loading platform capable of rotating freely so as to realize the purposes of applying constant load to the sample and ensuring that bilateral bending occurs at effective parts; the bending system comprises a bending die, a bending working platform and a sliding groove with special track, realizes the equal-amplitude reciprocating movement of the bending working platform along the sliding groove and drives the sample to occur repeated bending at the arc of the bending die. The invention also discloses a testing method for carrying out repeated bending under constant load by the equipment, which can carry out repeated bending performance test under constant load on even materials and materials with welding seams.