Short-focus projection lens and projection imaging system

The invention discloses a short-focus projection lens and a projection imaging system; the short-focus projection lens comprises a lens assembly which comprises a plurality of spherical lenses which are arranged on the same optical axis, and is used for the projection imaging of an externally inputted light beam; the spherical lens comprises a first meniscus lens, a first biconvex lens, a biconcave lens, a second biconvex lens and a second meniscus lens which are sequentially arranged. According to the short-focus projection lens provided by the embodiment of the invention, projection imagingcan be carried out on the externally input light beam by selecting the plurality of coaxially arranged lenses, and the plurality of lenses are all spherical lenses, so that the use of an aspheric lenscan be avoided, and the technical problems of high processing difficulty and high cost of the lens adopting the aspheric lens in the prior art are solved. Moreover, the short-focus projection lens provided by the embodiment o