The present invention provides a step counting method and a pedometer based on 3-axis accelerometer. The method of the present invention comprises: collecting a 3-axis acceleration; calculating sum of squares for the 3-axis acceleration to generate a standard acceleration; smoothing the standard acceleration to generate a processed acceleration; acquiring maximum and minimum of all processed acceleration during a period, calculating the difference between the maximum and the minimum, and setting a current time window according to the difference; determining whether there are at least three serial processed accelerations decrease progressively; if yes, confirming the collected time for the first processed acceleration of the at least three serial processed accelerations to be a current step starting time; determining whether a time difference between the two serial current step starting time falls within the current time window, if yes, adding step counting. The present invention can enhance the preciseness of step counting.