A new generation of building decoration board is made by using magnesium oxychloride as the core material, galvanized or color coated board as the surface layer [two layers], and high-strength adhesive. It is heated and pressed by a high-speed continuous automated forming machine, and then trimmed, slotted, and cut. It has strong fire resistance, with a water repellency rate of over 98% for magnesium oxychloride color steel sandwich panels. It does not deform or react chemically when exposed to water, and has high strength. The length of the sandwich panel can reach up to 10M to withstand two adults stepping on it, with good insulation and sound insulation effects.