Performance standards have important consequences for all the stakeholders in the assessment of L2 academic writing. These standards not only describe the level of writing performance but also provide a basis for making evaluative decisions on the academic writing. Such a high-stakes role of the performance standards requires the enhancement of objectivity in standard setting procedure. Accordingly, this study aims to shed light upon the usefulness of Objective Standard Setting (OSS) method in specifying the levels of proficiency in L2 academic writing. On the basis of the descriptive research design, the sample of this research includes the examinees and raters who were student teachers at the university level. Essay task and analytical writing scoring rubric were employed as the data collection tools. In data analysis, OSS method and two-step cluster analysis were used. The analysis results of OSS method based on many-facet Rasch measurement model (MFRM) outline the distribution of the criteria into the levels of proficiency. Also, the main findings in OSS method were validated with twostep cluster analysis. That is, OSS method may be practically used to help the stakeholders make objective judgments on the examinees' target performance.