The invention relates to an adjustable type downward-exhaust cyclone separating device which adopts the structure that the top of a cylinder body is connected with a barrelhead with a core pipe through a flange, the core pipe of the barrelhead is connected with a guide vane through internal threads and external threads, the bottom of the cylinder body is divided into two cavities, one cavity is an exhaust pipe, and the other cavity is an ash discharge pipe; an exhaust core pipe is embedded into the inner part of the exhaust pipe, the middle of the exhaust core pipe is connected with a stud, aposition which corresponds the wall of the exhaust pipe is provided with a key slot, the stud extends out of the key slot and is used for manually ascending and descending the exhaust core pipe, and a nut is screwed on the stud which is tightly screwed on the outer wall of the exhaust pipe by the nut so as to fix the exhaust core pipe; the bottom of the ash discharge pipe is connected with a supporting point, one end of the supporting point is connected with a cindervalve, the other end of the supporting point is connected with a screw rod on which a heavy bob is screwed, and the cindervalve is automatically closed by utilizing a lever principle. Because modularizing design is adopted, the distance between the guide vane and the exhaust core pipe can be adjusted, and the position of the heavy bob can be adjusted. The invention has convenient working condition change, easy gas-solid separation, easy maintenance and overhaul of the whole cyclone separating device and reduces the use cost.