Abstract: To investigate the flow characteristics of the full power natural circulation integral reactor under ocean condition,a series of experiments under rolling motion without heating were performed using test facility and followed theoretical analysis using flow model in non-inertial reference system.The loop flow rate changes cyclically with the rolling angle and no water flow into heat exchangers from heating channel through rise section.The amplitude of flow rate oscillations depends on facility configuration,flow resistance,position of rolling axis and rolling angle acceleration,and the amplitude can be reduced by decreasing the length of distribution channel.The phase lag between flow rate oscillation and rolling angle correlates with test facility dimension,and the quantity in direct proportion to rolling frequency and in inverse proportion to flow resistance coefficient.