A laser-assisted tunnel boring machine and a rock fragmenting method thereof belong to the technical field of tunnel engineering. Two rock fragmenting modes exist: a laser-cutter rock fragmenting mode and a cutter rock fragmenting mode, wherein the two rock fragmenting modes are switched by an intelligent control system; and for the laser-assisted rock fragmenting mode, hot fragmenting is mainly performed using lasers which assisted by water spray systems, to achieve the purposes of auxiliary rock fragmenting by laser radiation for hot cracking and water spray for quick cooling, and mechanical rock fragmenting for excavation.