The present invention provides a halogen-free dry film photosensitive resin composition, which comprises (a) 10.about.60 wt % of at least two kinds of acrylic resins having unsaturated carboxylic acid monomers as polymerized units; (b) 5.about.20 wt % of a photosensitive resin having at least two (meth)acrylate groups; (c) 0.1.about.15 wt % of a photoinitiator; and (d) 0.5.about.20 wt % of a thermo-curing agent. The resin composition of the invention is suitable for use as a photoresist in the process of producing printed circuit boards. The resin composition of the invention is particularly suitable for use in the surface of printed circuit boards or semiconductor packages as a protective dry film solder mask.