The invention discloses under-pressure taking and putting device and taking and putting methods for a corrosion monitoring rack. The taking and putting device comprises a taking and putting apparatus,a ball valve and a pedestal, wherein the ball valve is mounted on the pedestal; the taking and putting apparatus is mounted on the ball valve; the taking and putting apparatus comprises a top cover,an upper sleeve pipe, a spline shaft sleeve, a drive sleeve pipe, a lower sleeve pipe, a bearing block sleeve, a bearing, a taking and putting apparatus union, an upper pressure relief valve, a lowerpressure relief valve, a pressure gauge, a spline shaft, a lifting hand wheel, a lifting gear, a gear shaft, a driving ring handle, a driving ring, a movable joint, a socket head and a cylindrical compression spring. The pedestal comprises a pedestal shell, a pipeline, a plug cock, a hanging rod and a rack. According to the under-pressure taking and putting methods carried out based on the takingand putting device provided by the invention, corrosion monitoring racks of a test block or a probe, and the like, can be taken out and put into in a non-shutdown condition; meanwhile, the operation is safe, reliable, simple and convenient, and the one-man operation can be realized.