Anti-freezing heat-preservation water inlet system suitable for riverway bypass underflow constructed wetland

The utility model provides an anti-freezing heat-preservation water inlet system suitable for a riverway bypass underflow constructed wetland. A water inlet pipeline of the water inlet system comprises a non-winter water inlet pipeline and a winter water inlet pipeline; the arrangement height position of the non-winter water inlet pipeline is lower than the top of the filler and higher than the bottom of the maximum frozen soil layer in the area; the set height position of a water inlet pipeline of the constructed wetland in winter is lower than the bottom of the maximum frozen soil layer andhigher than the top of a water outlet pipeline covering soil layer; and the non-winter water inlet pipeline and the winter water inlet pipeline are respectively provided with a water inlet valve. Thesubsurface flow artificial wetland system is switched between the upper-layer water inlet pipeline system and the lower-layer water inlet pipeline system, the frozen soil layer formed at the low temperature in winter of the ri