The invention discloses a welding surface and near-surface crack depth detection device and mainly relates to the technical field of welding quality detection. The welding surface and near-surface crack depth detection device comprises a supporting seat which is provided with a supporting barrel, a screw is arranged in the supporting barrel and sleeved with a transmission pipe, one end of the transmission pipe is provided with a spring, a supporting rod is arranged at one end of the spring, and one end of the supporting rod is provided with a first universal wheel. The top of the supporting seat is provided with an outer barrel, an inner barrel is arranged in the outer barrel, one end of the inner barrel is provided with a first bevel gear, the screw is provided with a second bevel gear, a center rod is arranged in the inner barrel, the bottom of the center rod is provided with a supporting arm, and one end of the supporting arm is provided with a creeping wave probe. The welding surface and near-surface crack depth detection device has the advantages that the device can be quickly fixed into a large chemical engineering container and a pipe, welding surface and near-surface crack depths can be quickly detected, a missing detection phenomenon can be avoided, detection efficiency can be improved, and detectors' working strength is reduced.