We calibrated a capacitance diaphragm gauge(CDG) of 1,333 Pa range by using ultrasonic interferometer manometer (UIM) that was a national low vacuum standards system. And its uncertainties were evaluated according to International Organization for Standardization(ISO), they were named to A type uncertainty, B type uncertainty, combined standard uncertainty, and expanded uncertainty, We obtained that the combined standard uncertainties were $1.38 imes10^{-2}; Pasim3.03 imes10^{-1} $Pa and the relative uncertainties(combined standard uncertainty/standard pressure) were $2.3 imes 10^{-4};Pasim7.9 X imes10^{-3} $Pa for this 1,333 Pa CDG.