In this paper, the general structure of block cipher together with its related properties is firstly discussed, then the main non-linear component of s-boxes in block cipher is analyzed . as to the boolean function in binary field, we studied its non-linearity, linearity structure, output bit independence criterion ( big ), balance, completeness, strict avalanche criterion, propagation criterion, correlation immunity, linear approximation table and xor distribution table . we also discussed the pile-up lama used to compute the combination linear probability and showed an instance of its application 本文首先讨论了分组密码的一般结构及其相关特性,此外还有分组密码主要的非线性组成部分s盒。对于二元域上的布尔函数主要讨论了其非线性性、线性结构、比特独立准则、平衡性、完整性、雪崩准则、传播准则、相关免疫性、线性分布表及异或分布表等特性。对计算组合线性概率的迭加定理我们也进行了具体的讨论,并给出了运用事例。