The present invention provides an S-shaped acceleration and deceleration control method for changing speed and position of an object on line. The method comprises the acceleration phase speed planning, the deceleration phase speed planning, the constant speed phase speed planning, the real speed reduction point predication, the maximum speed processing, the surplus distance compensation, the online object speed changing algorithm and the online object position changing algorithm. An acceleration and deceleration discretization speed planning method is employed and the user input parameters are combined to calculate the operation time of a seven-phase speed planning phase. It is determined whether the maximum acceleration and the maximum speed can reach the criterion or not, the integration problem of a sampling period Ts according to the acceleration/deceleration acceleration, the acceleration/deceleration speed and the final position L after discretization is considered, and the real reachable acceleration/deceleration acceleration, the acceleration/deceleration speed and the feed rate are corrected. The S-shaped acceleration and deceleration control method for changing speed and position of the object on line greatly simplifies an original calculation formula and saves lots of operation time of a computer, and the surplus distance employs a one-time compensation method in the speed reduction process.