The invention belongs to the technical field of chemical equipment manufacturing. In order to overcome the defect of low heat transfer rate in a traditional heat exchanger, the invention discloses an oblate staggered pipe for the heat exchanger, which is formed by sequentially connecting a flat pipe, a circular pipe, a flat pipe, a flat pipe, a circular pipe and a flat pipe, the length of each pipe is identical, the two flat pipes adjacent to the circular pipes are mutually perpendicular and shaped like a cone and gradually transition to the adjacent circular pipes, the two adjacent cone-shaped flat pipes transition to the maximum sections of each other in parallel, with identical corresponding sizes, and the maximum section perimeter of each flat pipe is identical to the perimeter of each circular pipe. The oblate staggered pipe is suitable for a fixed pipe plate type heat exchanger, a U-shaped pipe type heat exchanger or a floating head type heat exchanger, complex flow taking a wave mode as a main characteristic is generated in fluid in a pipe side and a shell side, pure counter flow is formed inside and outside a heat exchanger pipe, stronger agitation is achieved due to a larger impulsive force particularly at the changing position of the pipe shape so as to form staggered turbulence, thereby a heat transfer process is reinforced to a larger extent. Moreover, the surface of the pipe wall can be automatically cleaned under the action of a medium in the shell side and scales are difficult to form.