Plywood grades are mainly classified by surface veneer defects, with the standard grading system covering Grade A, B, C and D. Grade A panels have flawless surfaces free of knots, gaps and color variations with smooth finishes. Grade B permits tiny knots and slight color differences. Grades C and D contain numerous knots, putty patches and obvious color variations with loose appearance requirements, suitable for hidden base layers.

Based on formaldehyde emission standards, plywood is categorized into E0, E1 and E2 grades, which are key references for furniture purchasing. E0 grade features ultra-low formaldehyde emission, ideal for enclosed indoor spaces such as wardrobes and cabinets. E1 grade meets general domestic indoor standards and delivers the best cost performance. E2 grade has relatively high formaldehyde content and is only permitted for outdoor and packaging applications away from human living areas.

Classified by service conditions and glue performance, plywood is divided into indoor grade, MR moisture-resistant grade and WBP boil-proof marine grade. Ordinary indoor plywood with MR glue can only be used in dry indoor environments. Panels bonded with WBP phenolic glue are waterproof and weather-resistant for construction formwork, boats and outdoor wooden structures. Special subdivisions like furniture grade and structural engineering grade are also available to meet diverse requirements for load bearing, waterproofing and decoration.