An inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Si and P in MnZn ferrites. The sample was digested by HNO3+HCl with microwave digestion followed by dilution with ultrapure water then the above two elements in the solution were analyzed directly by ICP-MS. The analytical elements were by introducing the helium gas into the octopole reaction system (ORS) to eliminate the polyatomic interferences caused by the high salty matrixes. The matrix effects and the instrument drift could be commendably calibrated with Y as internal standard element. The working parameters of the instrument were optimized. The NIST SRM 362 and NIST SRM 364 were used as standard reference materials. The results showed a good agreement between the certified values and the experimental results for three analytes. The detection limits for Si and P is 091 and 027 μg·L-1.