The spray-painted corrugated guardrail panels are produced using a zinc-plated spray painting process (including rust removal, phosphatization, and passivation). After the workpieces are pre-treated, this phosphatized film can prevent rust and enhance the adhesion of the spray painting layer. The surface of hot-dip galvanized zinc is smooth, and without the necessary pre-treatment before spray painting, the paint layer is prone to peeling and falling off. Therefore, proper surface treatment is indispensable.