The present invention relates to a dynamic adjustment method for adjusting a frame per second. The method includes steps of cyclically sampling a first image and a second image captured by an image capturing device based on a sampling time interval and uploading the first image and the second image to a server; executing an image variation rate algorithm on the server to acquire an image variation rate by comparing the first image with the second image; and adjusting the frame per second for the image capturing device to a first frame per second when all of the image variation rates within a first time window are less than a first threshold.