Ocean current power generation is forward-looking and important in the development of green energy technology. Taiwan Ocean Research Institute deployed an ADCP mooring in a field test site to collect current profile data of upper 500m during August, 2015 to March, 2016. As a whole, the mean current velocities fluctuated highly in the test site due to the reciprocating tidal current in Luzon Strait. Such fluctuations become an unstable situation which may further affect the efficiency of power generation. Therefore, this study suggests to move the power generation site northward to prevent poor efficiency caused by the current instability.