The invention relates to a conical connecting device for a tubular bus bar and a connecting method thereof. An inner side wall at a tubular bus bar coupling end and an outer side wall at an inner bushing connecting end are set as matched conical surfaces through the connecting device; and the tubular bus bar is tightly and fixedly coupled with an inner bushing by using a compressor through threaded contraction. According to the connecting method and the connecting device, convenient and rapid connection between the tubular bus bars as well as between the tubular bus bars and other equipment is realized, and connection between the tubular bus bars as well as between the tubular bus bars and other equipment is firm and compact; and the connecting device is elegant in appearance, has high tensile strength, uniform surface joint and excellent current conducting performance, and can be widely applied in the field of electric power transmission and transformation.