The design of functional coating requires consideration of multi-field and multi-scale effects from nanometer to meter，which remains a huge challenge for the design theory and simulation calculations of functional coating. There are still some unclear issues in the multi-scale simulation of functional coating，such as the need to strengthen the theory of multi-field coupling，improving the computational efficiency of multi-scale numerical methods，and significant model errors in large-scale turbulence numerical simulation. This article reviews the current status and trends of functional coating design theory and simulation，with a focus on discussing the latest developments in multi-field and multi-scale design theory，dynamic design theory，data-driven simulation methods，and strength and life evaluation methods. On this basis，future key development directions for functional coating design theory and simulation are proposed. Finally，it is pointed out that multi-field and multi-scale design techniques for industrial applications，dynamic load performance design，data-driven simulation，and building simulation software platforms are the technical difficultiesfaced by functional coating simulation design. Research suggestions for key technical difficulties are provided，providing reference for the subsequent application of multi-field andmulti-scale simulation in the field of functional coating design.