GS3is the first cloned gene that negatively regulates grain length and grain weight in rice. In this study,the coding region of GS3 in four main rice varieties（Longjing 31, Suijing 18, Longdao 18 and Longdao 21） from Heilongjiang Province was cloned and sequenced. Alternative splicing of GS3 was detected in each of the four varieties and a total of five splicing patterns were identified, three of which were recognized as functional according to the amino acid sequence analysis on their coding protein. As was shown in real-time quantitative PCR results, functional splicing types were the most abundant splicing patterns dominant in the four varieties and their expression decreased gradually during the panicle development. The expression varied significantly among the four varieties. GS3expression level in long-seed varieties was lower than that in short-seed varieties. It was concluded that GS3 gene played vital roles in negative regulating seed length during panicle development in the four varieties, which could be used as the target gene for genetic operation to improve grain shape.