A non-toxic water soluble photosensitive resin composition able to function as a solder mask coating comprises a polymer containing oxazolinyl, a photosensitive monomer, and a photo-initiator. These elements are all water soluble or water dispersible. The polymer containing oxazolinyl and the photosensitive monomer have a plurality of carbon-carbon double bonds. The polymer containing oxazolinyl and the photosensitive monomer are polymerized to form a dense cross-linking network structure when the water soluble photosensitive resin composition is exposed to ultraviolet radiation. A film using the water soluble photosensitive resin composition is also provided.