A projection lens disposed between an enlarged side and a reduced side is provided. The projection lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, which are sequentially arranged from the enlarged side to the reduced side. Refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are respectively negative, positive, positive, negative, positive and positive. A focal length of the third lens is greater than or equal to 20 mm and is less than or equal to 200 mm. An optical engine is also provided.