Abstract: A method for the determination of Cl, S, N, P, K, Cu, Zn and Br in biological samples by XRF with pressed-powder pellet sample preparation was proposed in this paper. Measurement condition and calibration model for N, the choice of internal standard for K, Cu and Zn measurements,the effect of measurement times on signal intensities are studied in details. The precision and accuracy of the method can meet the requirements of biological sample analysis. The method has been applied to the determination of these elements in practical biological samples and the results are in agreement with those from chemical analysis method.