The invention provides a workpiece butt joint positioning device and a workpiece butt joint method. The positioning device comprises a positioning pin, a sleeve, an attraction piece, a stopping piece and an elastic piece; the two ends of the positioning pin are the positioning end and the operation end; the sleeve is movably arranged on the positioning pin in a sleeving manner, the sleeve and the positioning pin can relatively move in the length direction of the positioning pin, and the positioning end of the positioning pin can extend out of the top end of the sleeve or be contacted in the sleeve; the attraction piece is arranged in correspondence with the top end of the sleeve and is used for attracting a workpiece to enable the sleeve to be detachably fixed to the workpiece; the stopping piece is fixed to the positioning pin, is located in the sleeve and can move in the sleeve along with the positioning pin; the elastic piece is arranged in the sleeve and abuts against the bottom end of the sleeve and the stopping piece; and when the positioning end of the positioning pin is contained in the sleeve, the elastic piece is in the compression state in the sleeve. The workpiece butt joint positioning device can be attracted to the workpiece, the positioning pin can be automatically popped out to complete positioning after the two workpieces to be subject to butt joint are aligned, the working efficiency is improved, and the operation safety is strengthened.