［Objective］ To meet the protection requirements for aluminum alloy substrates on aircraft skin，this study designed an environmentally friendly protective primer.［Methods］ The protective primer was developed using self-made polyurethane modified epoxy resin as the main film-forming substance and using chromium-free pigment filler and environmentally friendly solvent. Theeffects of resins，hardeners，and anti-rust pigments on the properties of paint films were systematicallyevaluated，and the compatibility of the protective primer with common sealants was discussed.［Results］The prepared protective primer exhibited excellent impact resistance，media resistance，low-temperature curing，and environmental resistance（including humidity，salt spray，and fungus resistance）. When the pigment-to-binder ratio was 1. 1，zinc phosphomolybdate，high-purity zinc molybdate andorganic corrosion inhibitor were selected as non-toxic anti-rust pigments. Through the synergistic effectof the three additives，the corrosion resistance of the paint film could be improved. At the same time，the primer has good compatibility with sealant PR1776 MB-2，and its peel strength was close to themaximum cohesive strength. MC-115 had little effect on the peel strength of the sealant and the paintfilm. When MC-115 was used in conjunction with the sealant PR2007 B-2，MC-115 could improve the peel strength.［Conclusion］In this paper，the prepared protective primer could meet the protectionrequirements of aluminum alloy substrates for aircraft skin，and had broad application prospects.