Abstract: As a common waterway improvement structure, spur-dike group changes fish habitats while altering the flow structure.To investigate effects of riverine spur-dike group on fish swimming behavior, we took juvenile grass carp as the research object and carried out a flume test of fish cluster swimming behavior, calculating its instantaneous power and energy efficiency during up streaming, to evaluate the up streaming behavior characteristics and energy dissipation of the test fish group.The results showed that: ① the slow-flow deep pool area behind the dam provided a stable habitat for the fish, and the higher the flow rate was, the more fish up streaming through the deep pool area.② The peak flow velocity along the up streaming path of the experimental fish group was at downstream of the dam, and the higher the flow rate was, the more pronounced the peak flow velocity hysteresis was.③ There was a linear correlation between the average frequency of tail swing of the fish and the flow rate, and the energy use efficiency of the fish was lower when the flow rate was higher; and the energy use efficiency was lower when the flow rate was lower than the flow rate.As the flow rate increased, the energy utilization efficiency of the fish population decreased, and when the relative Reynolds number was 213×10³ m^-1, the energy utilization efficiency of the fish population was the lowest.