A method and a device for curve velocity planning based on NURBS (non-uniform rational B-splines) curve interpolation as well as a numerical control machining route data processing method using NURBS curve interpolation velocity planning are provided. The method includes: obtaining numerical control machining route data with a NURBS curve; obtaining an acceleration within a parameter step length on the NURBS curve; comparing each the acceleration with a maximum allowable acceleration to determine an acceleration sensitive point and an acceleration sensitive interval; determining an intermediate point of the acceleration sensitive interval as a demarcation point of the acceleration and the deceleration; calculating a velocity value of the intermediate point as a target velocity; and planning the acceleration and deceleration of the acceleration sensitive interval based on the target velocity to obtain the numerical control machining route data with the planned NURBS curve.