Because of its light weight

excellent pollution flashover performance

high mechanical strength and easy maintenance

composite insulators are widely used in our country about ten million.But for its particularity

the traditional insulator detection methods cannot be completely used in the composite insulator’s detection

so it needs a new type composite insulator testing technology to promote the development of composite insulators.In this paper

we test the through ability of X-ray for composite insulator

and we get some parameters for the X-ray detection technology for composite insulator.Then we use the nondestructive testing technology of X-ray to detect lots of simulation defects in four areas of composite insulators（the umbrella skirt and sheath area

the mandrel area

the connection interface between the sheath and the mandrel

the metal parts area）

to detect some used composite insulators

with those parameters.From the many X-ray imaging drawing we get

it can be clearly see that the internal structure of composite insulators

that the defects type and their position

and it can be measured the sheath thickness and the mandrel diameter.The result can be used as a practical reference for the X-ray detection technology for composite insulators’ defect detection and type detection.