When the water depth is not deep enough or torrent occurs in a wild creek, a traditional propeller velometer can not put into the water body completely or could be carried away by torrent, selecting a radio current meter could conquer this problem in the field. This study, associated with the flume experiment, used a radio current meter to measure surface velocity and a propeller velometer as well as an electromagnetic velometer to measure point velocity. Under the conditions of 5.2 to 31.7 cm of water depth, 10,000 to 195,000 of Reynolds Number, this study got the results of correction factor for the radio current meter in clean water as well as straight channel and regression equation of mean velocity and surface velocity. In the future, the relationship between surface velocity and mean velocity in different sediment concentration is going to be carried out to keep with the character of velocity measurement in mountainous creeks in Taiwan.