Abstract:  A ring is called PM ring  every primitive ideal is a intersection of its some maximal ideals.In this paper,the property of PM-ring is discussed and the necessary and sufficient condition are given for the polynomial,centralizing,strongly normal extensions of PM-ring to be PM-rings.We also get some applications of the extensjon of PM-ring in group ring.

Key words: Brown-McCoy , ring;Jacobson , ring;Liberal , extension;PM-ring;polynomial , extension;strongly nomals extension