The invention discloses a horizontal multi-connection tube bundle heavy oil heat exchanger. The heat exchanger comprises a front end sealing head, a shell and a multi-connection tube bundle; the frontend sealing head is detachably connected with one end of the shell, and the other end of the shell is fixedly connected with a rear end sealing head to form a horizontal structure; the multi-connection tube bundle penetrates through the front end sealing head in a sealed mode to enter the lower portion of the interior of the shell and is immersed in a medium of the shell, and an evaporating spaceis formed in a cavity in the upper portion of the shell; and the multi-connection tube bundle is an integral-series-connection communicating channel formed by hermetically connecting a plurality of single tube bundles in an end-to-end mode through elbows. According to the novel tube-type heat exchanger, cleaning is achieved, sealing is reliable, and the tube bundle is convenient to disassemble; the problem of frequent blockage in the high-viscosity fluid cooling process can be solved; and waste heat of high-viscosity heavy oil is recycled to generate high-quality steam.