When the laser selective melting forming （SLM） steel products with large thickness variation in airspace engine such as centrifugal wheel and turbine stator are detected by conventional X-ray film photographic inspection （RT），quality problem of missed detection may exist since low tolerance of industrial X-ray films give rise to low testing coverage rate. In order to solve the problem，computed radiography testing （CR） was used to detect steel products defects，of which the thickness difference ranges from 5 mm to 20 mm. By comparing the CR image and the RT image，test results show that the tolerance of CR image is 3 times that of RT image. Taking linear defects of CR testing in centrifugal wheel as an example，through CT testing and physico-chemical testing，it is proved that defect detection sensitivity of CR is essentially the same as that of RT.