Abstract: Method of evaluation of uncertainty in measurement for the AFS determination of arsenic in instant fried rice was introduced.Evaluation of standard uncertainty of the calibration curve was calculated on the basis of the principle of method of least squares,and the sources of uncertainty of the analytical process were analyzed and distinguished fully and amply.The uncertainty in measurement of the AFS determination of arsenic was evaluated comprehensively.The results obtained in this work were considered to be valuable as a reference in the evaluation of uncertainty in measurement for other analytical methods,such as AAS,ICP-AES and etc.