we had designed and implemented a smart step counter with adaptive step detection algorithm that can enhance the accuracy of step detection using step amplitude. This algorithm can pick step count out over 99% of accuracy through the adaptive step detection algorithm. To prove the effectiveness of the new algorithm, we made a noise filtering process with the amplitude threshold from the amplitude of energy value that found out the detection error was increasing, and it''s the key idea of the variable amplitude threshold that can be adapted on the continuous data evaluation. The experiment results shows that the adaptive step detection algorithm can catch the average step count accuracy up to 98.9% at 10 Hz sampling rate and 99.6% at 20Hz sampling rate.