The utility model discloses a chaotic channel. The chaotic channel comprises multiple orthogonal geometrical basic units so that a novel heat transmission channel is formed. Fluid flows through the orthogonal geometrical basic units in a periodic and repeated manner in the channel, so chaotic convection is formed, thereby obtaining a better heat transmission effect. The utility model also provides a clapboard and fin structure corresponding to the chaotic channel. In a low Reynolds number range, het heat transmission performance of a fin formed by the chaotic channel is higher than that of a sawtooth fin and a flat fin. When the Reynolds number is smaller, friction factor of the chaotic fin is smaller than that of the sawtooth fin. The smaller the Reynolds number is, the better the comprehensive performance of the chaotic fin is. Compared with common fluid, a novel chaotic plate-fin heat exchanger has a better thermal power performance in a low Reynolds number.