The BR-III-B phosphate coating agent is a phosphorizing liquid that may be applied under both ambient and higher temperature. After subjected to phosphorizing treatment, a steel work piece will take on an even and solid phosphate coating. The product may be used for surface treatment prior to painting. Due to the solidness of coating, it is especially suitable for use in home electric appliance and automobiles, where good anticorrosion performance and adhesive force are required.