We think that it's not suitable for us to use the four rules about the true definition in formal logic as the basic demands for the mathematical definition. We can instead make the rules concerning the constant individually in the mathematical basic conception. 把形式逻辑关于真实定义的四条规则用来作为数学定义的基本要求是不恰当的,可以针对数学的三类基本概念中的不变个体制定具体的定义规则。