This article is about confining the meaning of freedom of research that Constitution ensures, accordingly, academic freedom. Thus it is required to convince that what is academic research. The definition of academy in this article refers to one acquiring knowledge by way of indicating the logical relations in natural and cultural phenomena, and a distinguishing feature is devoting himself to rational certifications in a planned way. Academic freedom does have its limitations. First of all we can deduce the internal boundaries of academic freedom from academy itself. Violation of academy is here involved, for damage to ethics of academy; it is no longer regarded as an ethical conception of academy. There are also external boundaries of academic freedom, and they come from public interests or people's rights conserved. The four main legislated advantages that restrict academic freedom are personal rights, environmental protection, human bodies and beings, and human dignity. Meanwhile we will discuss practical cases about freedom of research restricted by these four legislated advantages.