In chapter ii, first, we give a concise account of the theory of algebraic invariant . second, by using the methods of algebraic invariants, we get the classifications of fifth-order binary forms 第二章首先简单介绍代数不变式思想;然后利用代数不变式的思想,对二元五次代数多项式进行代数分类;最后由此得到系统的12种标准形。