The present invention discloses a halogen-free resin composition and a method for manufacturing a prepreg and a laminated board by using the halogen-free resin composition. The halogen-free resin composition is prepared by dispersing the following components in an organic solvent, wherein the components comprise, by weight, 10-100 parts of a halogen-free epoxy resin, 10-80 parts of cyanate, 10-70 parts of an anhydride curing agent, 10-100 parts of a benzoxazine resin, 0.01-1.0 part of a curing accelerator, 1-15 parts of a toughening agent, 0-50 parts of a fire retardation agent, and 0-100 parts of an inorganic filler, and the solid content of the halogen-free resin composition is 30-70 wt%. The prepared prepreg and the copper foil-clad laminated board have characteristics of good heat resistance, high glass-transition temperature, low water absorption rate, excellent fire retardation, low dielectric constant and low dielectric loss factor.