The adaptive filter is an effective method to dealing with such kind of non-steady random signal of the heart rate. The algorithm of clipped- error LMS algorithm with variable step size of segmenting type was proposed. We adopted auto-regression predict filter estimating the noise of heart rate signals through Doppler ultrasound sensor. We used it as the reference signal of the adaptive noise cancelling system, its result is to remove some noise of main input, it made SNR raise by about 36 dB, it realized the abstraction of the heart rate signals.