As device feature size continues to decrease, the resolution of conventional lithography which is restricted by diffraction limit, have been approaching to the theoretical limit and the cost is very high. Maskless lithography is a potential program to solve the high cost caused by the rising price of the mask. Maskless lithography has been widely used in nanofabrication, mask direct writing and low-volume integrate circult (IC) production because of its low cost, high flexibility and short production cycle. Currently, spatial light modulator (SLM)-based maskless lithography made some progress in improving the resolution and throughput. Both the theory and experiment of SLM-based maskless lithography achieved good results. A review on the principle, feature and progress of maskless lithography based on SLM is presented.