The minimal energy dissipation of ideal velocity profile and the velocity function of general acc/dec algorithms were deduced. Subsequently, according to the relation between the velocity curve and the power dissipation in the motor, the energy dissipation function per step under the S curve velocity was derived, and its minimum was solved with Matlab. It is a new discovery that the optimal velocity can be gained when t1 of trapezoidal algorithm and quadric spline curve is T/3 and T/6 respectively; t1 and t2 of S curve algorithm is 0.01T and 0.32T respectively; t1 and t2 of AS curve algorithm is 0.01T and 0.35T respectively, and R2 is 0.98. At last, the energy dissipation of acc/dec algorithms were calculated under the conditions of different time parameter settings, and were compared with the ideal velocity, more, there were obvious differences in energy dissipations of different algorithms. It is very useful to set the time parameters of acc/dec algorithms and improve the efficient of motor in acc/dec motion control. 