Abstract: Briefed in the paper are the characteristics, work principles and operation procedures of the pitch diameter gauge and ovality gauge used to check coupling threads. The errors of the stand-off measurement and measurement errors made by pitch diameter gauge and ovality gauge are analyzed and compared. Based on relevant operation results, it is concluded that under the precondition that all the thread element data like taper and pitch remain consistent, it is feasible to substitute the pitch diameter gauge and the ovality gauge for the thread work gauge.