Small optical lens applied to monitoring and vehicle-mounted occasions

The utility model discloses a small optical lens applied to monitoring and vehicle-mounted occasions, which comprises a lens cone. A first lens, a second lens, a third lens, a fourth lens, and an optical filter are sequentially arranged in the cavity of the lens cone from the object side to the image side. The first lens is a crescent glass spherical lens of negative power. The second lens is a crescent plastic aspheric lens of negative power. The third lens is a crescent plastic aspheric lens of positive power, and the concave surface of the third lens is arranged to face the image side. The fourth lens is a drum-shaped plastic aspheric lens of positive power. The fifth lens is a crescent plastic aspheric lens and the concave surface of the fifth lens is arranged to face the object side. The small optical lens applied to monitoring and vehicle-mounted occasions is ultra-wide in field and small in size.