A lens module (50) and a 3D printer (100) comprising same. The lens module comprises a first lens (L1), a second lens (L2) and a third lens (L3) sequentially and coaxially arranged in the transmission direction of incident light. The first lens, the second lens and the third lens are all meniscus lenses. The first lens comprises a first curved surface (S1) and a second curved surface (S2). The second lens comprises a third curved surface (S3) and a fourth curved surface (S4). The third lens comprises a fifth curved surface (S5) and a sixth curved surface (S6). The first to the sixth curved surfaces are sequentially arranged in the transmission direction of the incident light, and the curvature radii of the first to the sixth curved surfaces are sequentially −200±5%, −100±5%, −80±5%, −150±5%, −100±5% and −70±5% in a unit of millimeter. By means of the lens module, the printing efficiency of the 3D printer is high and it is convenient to carry out printing of ultra-large workpieces.