Bats are well known for echolocation.Both FM and CF-FM bats use echo from self-generated ultrasonic pulse.There have been some study on the local motion on their head(ears and noseleaf)which happens all the time during flying and hanging.But it doesnt reach a general consensus among researchers why bats flap their ears.From the data acquired by high speed video camera and ultrasonic microphone in lab,we try to find a relationship between motion of ears and ultrasonic pulse.After drawing the spectrogram of sound,we use a threshold filter to get the graph of each pulse and parameterize each pulse.And we get the magnitude of motion frame by frame using optic flow method.By the analysis of data,we find some correspondence between acoustic pulse and motion.