A halogen- and phosphorus-free thermosetting resin composition is provided, which is mainly a varnish resin formed by mixing a mixture of two curing agents, an epoxy resin mixture, and an inorganic additive. The mixture of two curing agents is formed by mixing a phenolphthalein modified benzoxazine phenol aldehyde curing agent and an amino triazine novolak, and the epoxy resin mixture is formed by mixing an epoxy resin having an oxazolidone ring or a polyamide-imide-modified epoxy resin and a Bisphenol F epoxy resin.