Abstract: With the problem of on-line inspection apparatus of pressure pipeline with the insulation in Chinese petroleum and chemical industry, a set of on-line inspection apparatus of pressure pipeline with the insulation based on CBS is developed in this paper. The main capability index of apparatus: the diameter scope of the inspected pipeline hasn’t been limited; the insulation thickness is less more than 145mm; the wall thickness of the steel pipeline is less more than 40mm; the accuracy is 1.0 mm. The basic principle and the exact structure design of the inspection apparatus has briefly explained in this text. It has also listed the double-hole and single-hole plane scanning experiment result of the inner-surface of the pipeline with 40mm thickness outer-laying aluminum scarfskin insulation.The experiment result has demonstrated when the apparatus is applied to inspect practical pipeline, the inspection result is very precise, and the error is in the allowance scope.