An optimized formulation of WY shield tail sealing grease is obtained by means of orthogonal test. The shield tail sealing grease is composed of highquality base oil, compound viscosity index improver, natural biodegradable fiber and particulate filling medium. Hereafter, the watertightness and pumpability of the mentioned grease are characterized by using selfmade watertightness test device and melt flow rate device. Comparison and contrast is made between the property of the mentioned grease and that of similar products made in China and abroad. The results show that the watertightness of the mentioned grease is consistent with that of CONDAT product and no water leakage occurs under 3.5 MPa pressure, while the pumpability of the mentioned grease is 2~3 times of that of a kind of grease made in China.