To utilize the incomplete information effectively

a diagnostic approach was proposed based on(α

β

γ) connection degree tolerance relation.Firstly

the incomplete diagnostic information system was defined for equipments' incomplete information

also(α

β

γ) connection degree tolerance relation was defined for their consistent

inconsistent or uncertain relationships.Then

attribution reduction method was researched based on the new tolerance relation

and new diagnostic method was designed based on optimized inconsistent degree.At last

the designed method was validated with the diagnosis of some-type controlling processor.Cases show that this approach can deal with incomplete information effectively

and enhance the diagnostic accuracy remarkably.