The invention discloses a heat exchanger for particle coagulation. The heat exchanger comprises a coil pipe and fins, wherein a mounting hole is formed in each of the fins; the mounting holes in the fins sleeve the coil pipe; each fin consists of a top, a transition section and a bottom, the top is located at one end of the transition section, and the bottom is located at the other end of the transition section; the fins are vertically arranged; the bottoms of the fins are arranged at the ends, close to the ground, of the transition sections; the tops of the fins are located at the ends, far away from the ground, of the transition sections; the top surfaces of both the tops and the bottoms are arc surfaces; the widths of the tops are larger than those of the bottoms; and the transition sections are in smooth transition that the widths are gradually reduced from the tops to the bottoms. According to the heat exchanger, as the fins adopting special structures are fixed on the coil pipe, acid fluid drops attached to the drop-shaped fins can drop under the fins to be conveniently collected, accordingly, the acid fluid drops are prevented from corroding equipment nearby, and the separation effect of the heat exchanger can be improved.