A projection lens, a projection device and an optically-induced microparticle device are provided. The projection lens includes an aperture, a first and a second lens groups. The aperture, the first and the second lens groups are disposed on a projection path of an image. The aperture is between the first and the second lens groups. The first and the second lens groups are suitable for interchanging with each other to switch the magnification ratio. When in a first state, the first lens group is between the object and the aperture and the second lens group is between the aperture and a projection surface, herein the projection lens has a first magnification ratio. When in a second state, the first lens group is between the aperture and the projection surface, and the second lens group is between the object and the aperture, herein the projection lens has a second magnification ratio.