The invention discloses a locking mechanism for a fire-resistant overhanging eave with an automatic stretching function. The locking mechanism comprises a left plate and right plate fixed to the wallsurface of an outer wall , a rolling rod clamped between the left plate and the right plate and used for rolling and storing a fire-resistant cloth, a limiting groove formed in one end of the rollingrod, and a thermal stretching-retracting locking mechanism fixedly connected with the left plate or the right plate, matched with the limiting groove and used for locking the rolling rod. The thermalstretching-retracting locking mechanism comprises a limiting strip clamped into the limiting groove and used for achieving locking of the rolling rod, a limiting baffle attached to the limiting strip,a base bottom plate vertically connected with the limiting baffle, and a thermal stretching-retracting rod with one end being connected with the base bottom plate. The locking mechanism has the advantages of simple structure, reliable movements and the like and has quite high practical value and popularization value in the technical field of fire fighting.