The influence of rf(radio frequency)frequencies on long time evolution of atomicity density of two-component Bose-Einstein condensations is studied. The results demonstrate that the atomicity density of BEC presents a quantum collapse and revival(C-R),which is typical in quantum mechanics when the rf frequency is small enough and the time is fairly long. When the rf frequencies increased and the time prolonged,the oscillation curve of C-R declines as a whole with time.