A new method was developed for the determination of twelve different trace impurities in high purity chromium by ICP-MS after chloroformylation separation. The interferences on analytes and the pollution of sample introduction system were efficiently avoided by separation impurity elements from matrix chromium which makes use of chromyl chloride’ low boiling point. The influences of temperature and dosage of acid separation effects were studied. The content of 50V and 50Ti changing with the amount of residual chromium in sample solution was determined. The analytical results proved to be accurate and validated by comparing the proposed method with ICP-OES and AES with D. C electric as the excitation. Under optimized conditions, over 99.99% of the matrix chromium was removed by chloroformylation separation at 130 ℃ with the acid addition of 12 mL for 2 h, which eliminated the matrix effect and spectra interference in the following ICP-MS detection. It showed that the detection limit of the method was 0.000 01%～0.000 06%; the RSD was 1.7%～5.8%; and the recovery of standard addition was 90%～104%. The method is simple, applicative and suitable for the determination of impurities in high purity chromium of 99.99%.