Sintered magnets are widely used because of the excellent magnetic properties,it is reported that highest magnetic energy product reached 59.6 MGOe.It was usedthe low prices of rare earth element Ce instead of rare earth Nd,which have different performance of permanent magnet,in order to reduce the cost of sample preparationand satisfy differentmarketdemands.The tempering process of magnets preparation affects the grain boundary phase distribution between primary phase particles.The process makes theprimary phase particles separated uniformly by grain boundary phase,which improved the magnet coercive force.At the same time the processchangecontact area of the grain boundary and primary phase particles,which increasethe galvanic corrosion and affects the corrosion resistance of the magnet.Ce content accounted for weight ratio20% of total rare earth with excellent performance of sintered permanent magnet was made by double main phase ways in our laboratory,these magnets are named Ce20 in following content.It was studied of the corrosion resistance of the Ce20s with different high temperature state (HS) and tempering state (TS) samples.