The invention provides an intermediate drive spindle mechanism for the machining of an axle, and aims to solve the problems of time consumption and labor consumption of feeding, blanking and assembly clamping of the axle with a relatively large size. A key point is that a spindle is arranged in a headstock through spindle bearings, wherein a spindle gear sleeves the spindle, and is fixed together with the spindle; the spindle gear, an intermediate gear and a transition gear are sequentially meshed; the intermediate gear is arranged on a support shaft through intermediate bearings, and rotates relative to the support shaft; the transition gear is connected to a spline sleeve through a key; a spline shaft is matched with the spline sleeve. The intermediate drive spindle mechanism has the beneficial effects that the intermediate drive spindle mechanism can move leftwards and rightwards, rotating power can be transmitted, and the machining efficiency is improved.