Today, soil heavy metal pollution is serious. It’s necessary to design a handheld, field and in-situ soil heavy metal detector. A lens is used to focus the laser beam on the sample. A paraboloidal mirror and a separate lens group are used to collect the plasma optical signal into the optical fiber. A paraboloidal mirror and a gluing lens group are used to image the target point to the matglass. The size of the light spot on the sample is suitable; the coupling efficency of the light which is collected into the optical fiber is high and the numetical aperture of the light satisfies the requirement of the selected fiber; the target point is imaged clearly to the matglass; the length, width and height of the whole optical system are separately less than 30cm, 25cm and 10cm, and therefore the system is compact, small-sized and easy to carry. The result shows that the system is suitable for non-contact, field and in-situ soil heavy metal detection.