The invention provides a tailstock feeding control method for a floating tapping numerical control lathe. According to the tailstock feeding control method for the floating tapping numerical control lathe, a connecting device for connection and disconnection between a saddle and a tailstock of the numerical control lathe is adopted. The connecting device comprises a centering assembly, a rotating arm assembly, a driving assembly and a screw tap assembly. The screw tap assembly is installed in a sleeve of the tailstock of the numerical control lathe. The centering assembly comprises a centering shaft and a centering sleeve provided with an inner taper hole. The rotating arm assembly comprises a rotating arm, a rotating shaft, a shaft sleeve and two limiting press blocks. The driving assembly comprises a pair of belt drive assembly, a driving motor, a resetting switch and a controller. The controller is installed in a lathe power distribution cabinet. The resetting switch is installed in front of the saddle of the numerical control lathe. The driving motor is fixedly connected with the tailstock of the numerical control lathe and electrically connected with the controller.