Abstract: To address the needs of food safety monitoring, a certified reference material (CRM) for calcium and phosphorus in chicken formula feed was developed. The CRM underwent sample pretreatment using microwave digestion, followed by quantification of calcium and phosphorus content using an inductively coupled plasma optical emission spectrometer (ICP-OES). The homogeneity and stability of the CRM were systematically analyzed, and uncertainties were evaluated. The results demonstrate that the CRM exhibits excellent homogeneity and stability, with certified values of 1.221% for calcium and 0.687% for phosphorus, and expanded uncertainties of 0.117% and 0.091% (k=2), respectively. The CRM can be stored for 16 months at −18 ℃. This development fulfills the requirements for feed quality and safety monitoring and provides essential technical support for calibration, quality control, and method validation in the analysis of calcium and phosphorus in formulated feed samples.