Abstract: Isoelectric focusing was used to identify the seed purity of hybird rice. The study shown that at least one pair of protein bands with parants characteristics were found in hybird seeds of Boyou 998. The testing results, which was made in lab by distinguishing protein bands with parants characteristics, are much similar to those from field testings. Consequently, isoelectric focusing could be potential technique applied to identify the seed purity of hybird rice in the future.