The invention provides a quick pipeline connecting structure and a mounting and dismounting method, and belongs to the field of pipelines. The problem that existing pipeline connecting is low in strength and poor in sealing performance is solved. The quick pipeline connecting structure comprises an upper pipeline, a lower pipeline and a connecting device. The connecting device comprises an upper connecting component connected with the upper pipeline, and a lower connecting component connected with the lower pipeline. The upper connecting component comprises an upper quick connecting pipe, an upper connecting pipe and an upper connecting plate. The upper connecting component further comprises an upper fastener penetrating through the upper connecting pipe and the upper pipeline to be fixed.The lower connecting component comprises a lower quick connecting pipe, a lower connecting pipe and a lower connecting plate, and further comprises a lower fastener penetrating through the lower connecting pipe and the lower pipeline to be fixed. A circular-ring-shaped upper baffle ring is fixed to the outer wall of the bottom end of the upper quick connecting pipe coaxially. A circular-ring-shaped lower baffle ring is fixed to the inner wall of the top end of the lower quick connecting pipe coaxially. The quick pipeline connecting structure further comprises an adjusting pipe sleeving the outer side of the upper quick connecting pipe, the inner diameter of the upper quick connecting pipe is the same as the outer diameter of the lower quick connecting pipe, and a circular-ring-shaped sealing pad is fixed to the top end of the lower baffle ring. The connecting structure can be used for connecting pipelines in a high strength and high sealing performance manner.