This assessment program was established by Guangdong Inspection and Quarantine Technology Center (IQTC) to evaluate the detection capability of aflatoxin B₁ in peanut oil approved by Certification and Accreditation Administration of the People''s Republic of China (CNCA). MethodsThe assessment was performed according to ISO 13528:2005, CNAS-GL02:2006, CNAS-GL03:2006 and the international harmonized protocol for proficiency testing. The homogeneity of samples was assessed by F-test and S S≤0.3σ_p,the satiability was assessed by t-test. The median was used as assigned value to calculate a z-score which was used as a numerical indicator to show participants’ performance in the program.ResultsLaboratories which were identified as “unsatisfactory or questionable” had one chance for a second-round test. Finally, 88samples were observed as satisfactory, 1sample as questionable and 2samples as unsatisfactory. Conclusion Most of domestic related laboratory possess good detection capability of aflatoxin and could meet the requirements of international proficiency testing standards.