The invention discloses a motion noise interference eliminating method suitable for a wearable heart rate monitoring device based on a photo plethyamo graphy. The method can effectively eliminate motion noise interference and improve heart rate value monitoring precision. According to the method, an NLMS self-adapting filter and a Mallat algorithm are combined, and six-axis acceleration signals generated by a triaxial accelerometer and a gyroscope are selected as motion reference signals of the self-adapting filter to eliminate part of motion noise interference. The method takes full consideration of complexity and calculation amount of the algorithm, the characteristic that motion noise and heart rate noise are equal in frequency, and other noises and the heart rate noise are not overlapped in frequency is utilized, and through two efficient and low-complexity algorithms, different noises are eliminated step by step, and the purpose of calculating the heart rate in real time is achieved. The low complexity of the method guarantees practicability of the method on the wearable heart rate monitoring device.