Plane lens and illuminating lens device based on plane lens

The invention discloses a plane lens and an illuminating lens device based on the plane lens. The plane lens comprises a transparent lens body. The transparent lens body is provided with a bottom face, a total-reflection face and an emergence face. The bottom face is provided with an incidence groove used for containing a light source and faces towards the interior of the transparent lens body. The side wall of the incidence groove serves as an incidence face. According to the improvement of the technical scheme, the incidence face comprises a small-angle incidence face body and a large-angle incidence face body; a transition curved face is arranged between the total-reflection face and the emergence face; the total-reflection face comprises a first total-reflection face body and a second total-reflection face body. The illuminating lens device comprises one or more plane lens. The plane lens and the illuminating lens device based on the plane lens have the advantages, which cannot be achieved by existing products, that the surface smoothness is good, cleaning is convenient, and the light-pervious efficiency is high.