In this paper, the process as wall as the results of the barometrical pressure test performed in Wuhan in Oct. 1984 for the three gravimeters(C-327, w-1143, w-1210)has been given, and the barometrical pressure correction to the observed gravity of the Lanzhou-Tianshui-Wudu Gravity Net (LTWGN)has been estimated. The results of the test for the three gravimeters are k327=0.816, k1143=1.013, k1210=3.434(ugal/mmHq)respectively. Based on the data obtained from the barometric pressure correction, the possible effect of this correction is discussed.