The invention relates to a detection apparatus for reliability of welding positions of metal. The detection apparatus comprises an upper base plate, a lower base plate, supporting columns and a workbench, wherein the upper base plate is provided with a mobile through hole and tracks; the workbench is provided with a material delivering through hole and ball rolling through holes; the lower base plate is provided with elevating cylinders and an elevating platform; a synchronous belt conveying device and a ball rolling support are arranged on the elevating platform; the rear end of the mobile through hole is provided with a first driving motor, a first screw, a first bolt joint member and a first slide block; a pre-compaction cylinder and a compaction cylinder are arranged below the first slide block; the left and right sides of the workbench are symmetrically provided with a pair of side cylinders; the front end of the mobile through hole is provided with a second driving motor, a second screw, a second bolt joint member and a second slide block; an impact cylinder is arranged below the second slide block; and a laser range finder and a pressure sensor are also installed. The invention also provides an application method for the detection apparatus. The application method comprises the following steps: feeding; position adjustment; material delivery; compaction; impact; data collection and analysis; material returning; etc.