Abstract: Traditional Fortran compiler has been manual. This paper discusses the experience of developing KJFOR. the parser and lexical analyzer of the vector Fortran language which will be performed on KJ8920 computer. surported by Unix utilities Yacc and Lex. There is neither reduce /reduce nor shift/reduce conflict in the BNF describing the grammar of the vector Fortran language. KJFOR is powerful in looking-ahead to recognize the reserved words. KJFOR can point out exactly the error location in source.