The current meter, when measuring flow velocity with a suspended cableway, always composes a vertical angle which affacts result of velocity measurement.Various relationship between dip angle and flow velocity of M25-1 vertical-axis current meter and LS68-1 horizontal-axis current meter is discussed. The research shows that the larger vertical dip angle results in the larger error of the now velocity. Flow velocity of LS68-1 horizontal-axis current meter is acceptable when dip angel is within 10 to 30 However,the measuring velocity is systematic shifting smaller when the dip angle is over 30 comparing with the actual velocity. Two methods that may narrow the error of measuring flow velocity are discussed.1).The LS68-1 horizontal-axis current meter is recommended when the dip angle is small,and LS25-1 vertical-axis current meter can be used when the dip angle is large.2).Choose suitable lead fish with reasonable type and weight.