A thermosetting resin composition and a prepreg are provided. The thermosetting resin composition includes a maleimide resin, a cyanate ester resin, and a crosslinking agent. The crosslinking agent is a silane-modified diallyl bisphenol compound whose structure is represented by Formula (1): in Formula (1), X is a linear or branched C1 to C6 alkyl, cycloalkyl, or sulfonyl group, R1 is a linear or branched C1 to C6 alkyl or aryl group, R2 is a C1 to C6 alkyl group, R3 is a functional group with a crosslinkable double bond, and n+m is a positive integer from 1 to 8.