The invention discloses a mechanical explosive-filling device and a method for filling explosive by using the same. The mechanical explosive-filling device comprise a forced air input end connector, a forced air valve and a three-way pipe which are sequentially connected, wherein the forced air valve is connected with a first end of the three-way pipe, which is in the horizontal direction, one end of the three-way pipe, which is perpendicular to the horizontal direction, is connected with a first pagoda-shape connector, an explosive input pipe is connected with the first pagoda-shape connector, a second end of the three-way pipe, which is in the horizontal direction, is connected with a second pagoda-shape connector, and an explosive output pipe is connected with the second pagoda-shape connector; the mechanical explosive-filling device also comprises a cylindrical small-hole component, the hole diameter of one end of the small-hole component is larger than the hole diameter of the other end of the small-hole component, the end with a large hole diameter is longer than the end with a small hole diameter, the end with a large hole diameter is in matched and connected with the inside of the forced air valve, and the end with a small hole diameter is in matched and connected with the inside of the first end of the three-way pipe, which is in the horizontal direction. By using the mechanical explosive-filling device and method for filling explosive by using the device disclosed by the invention, the problem that ANFO (ammonium nitrate/fuel oil) explosive is filled difficultly can be solved, and labor cost for explosive filling and the number of drilled holes are lowered; moreover, the explosive-filling device is simple and is convenient to install.