Based on the domestic and foreign classification of the tiered health care system(THCS), This paper studies the nature of the THCS. THCS is regarded as a professional mode of diagnosis and treatment，which are divided on the surface, but combined in practice. And this mode depends on the benign operation and coordination of the medical management system. Then, the current THCS in China is analyzed，The main reason for the difficulty in establishing the current grading system is that administrative hierarchy system leads excellent medical resources to be aggregated in the higher level hospital; two- way referral system is not perfect; good medical culture has not yet formed. At last, suggestions about the reform of the THCS system are put forward.