<p>To eliminate the tangential discontinuity of continuous line segments and time round-off error of velocity planning in numerical control machining, a dynamic velocity planning methodology incorporating round-off error elimination strategy for micro line segments is proposed in this paper. The corner smoothing curve is constructed by the arc-length parameterized clothoid curve to obtain the curve of continuous curvature. More importantly, the corner curve is dynamically reconstructed relying on the suboptimal solution of the best corner velocity to improve the planned corner velocity. Based on the asymmetric S-shape velocity curve, a round-off error elimination strategy with quadratic correction is proposed for the time rounding error in velocity planning. The interpolation time is adjusted to ensure it is an integer multiple of the interpolation period. By integrating the round-off error elimination strategy with the look-ahead velocity planning strategy, a look-ahead planning strategy with bidirectional backtracking is proposed to realize continuous velocity planning and solve the problem of jerk exceeding the limit caused by the round-off error elimination strategy. Simulation and experiment show that the algorithm proposed in this paper can effectively realize online corner smoothing and velocity planning of continuous line segments, eliminate velocity fluctuations caused by time rounding errors, and ensure that kinematic parameters do not exceed the allowable range.</p>