An embodiment of the invention discloses a maskless optical lithography system which comprises a lighting optical subsystem, a spatial light modulation subsystem and a projection optical subsystem. The lighting optical subsystem is used for emitting light beams with uniform energy distribution and parallel to an optical axis of the spatial light modulation subsystem; the spatial light modulation subsystem comprises a digital optical fiber bundle device and a controller connected with the digital optical fiber bundle device; the digital optical fiber bundle device is formed by multi-beam micro-sized outsourcing optical fibers, optical fiber combined beams arrayed in a default arrangement and symmetrically distributed on two sides, multiple array distributed connection chambers and pixel switches located in slits of the connection chambers; the projection optical subsystem comprises a projection lens assembly and a substrate, and the projection lens assembly is used for segmenting a maskgraph and then performing splicing according to a zigzag route to have images formed on the substrate. The digital optical fiber bundle device can serve as a dynamic mask generation device and can achieve image translation in real time with high efficiency and low cost, image quality is improved, and exposure is increased.