This research aimed to develop formative assessment rubrics for enhancing students' performance on Thai percussion instruments using the Many-Facet Rasch Measurement Partial Credit model (MFRM-PCM). Samples were high-school students playing four types of Thai instruments and the raters who were qualified and properly trained. The research instrument was rubrics used for assessing students' Thai percussion instruments skills. Each item contained five quality levels. The research methodology was divided into three phases, that is, the synthesis and verification of content validity, pre-testing of the psychometric properties and the assessment design, and the verification of the rubrics' psychometric properties. Four facets of the MFRM-PCM including students, raters, musical instruments, and items facet were employed to analyze the psychometric properties of the developed rubrics. It was found that the rubrics developed for assessing performances of Thai percussion instruments with the MFRM-PCM contained eight criteria and 12 items. The quality levels of the items after the category's effectiveness analysis were reduced ranging from two to three quality levels.