This standard specifies a comprehensive method for measuring the contact angle of nanofilm coatings on flat substrates. It covers the entire process, from terminology definitions, measurement principles, required testing equipment and environmental conditions, to specific sample preparation, analysis procedures, result calculation, and report preparation. The key instrument for implementing this standard is the contact angle goniometer. Such instruments typically employ optical imaging and image analysis technology, using high-resolution cameras to capture droplet contours and automatically calculate contact angle values based on relevant theoretical models. This standard aims to provide a unified and reliable technical basis for evaluating the surface wettability of nanofilms.