The present disclosure provides: a thermosetting resin composition comprising: (a) bisphenol M-type epoxy resin; (b) bisphenol M-type cyanate ester resin; (c) polyphenylene ether having two or more vinyl groups at both ends of a branched chain, or oligomers thereof; and (d) a cross-linking curing agent, a prepreg comprising the composition, and a printed circuit board. The printed circuit board simultaneously has an excellent low dielectric loss characteristic, a great moisture-absorbing and heat-resistant characteristic, a low thermal expansion characteristic, thermal stability and the like.