Abstract: In recent years,the precision of tropical cyclones (TC) operational positioning is about 20-30km on the West-North Pacific (WNP) in China and America. It is noted that the measures are the best positions sited by China or America. But the best positions aren't the true positions of TC,and the best positions sited by China and America are different: the average error is 54.4km,more than the operational error. So,the precision of operational positioning may be larger than present assessment by China or America. The differences space-time characters of the best positioning between China and America are analyzed in this paper,with attention paid to operational forecast and the research achievements applide to the WNP TC.