In recent years

China s serious disease insurance has achieved remarkable development

but its institutional construction still lags behind. There is no unified understanding of the nature and the law application of serious disease insurance

which affects the sustainable development of the system. Under the Chinese insurance legal system

combining with the analysis of the difference between social insurance and commercial insurance

the serious disease insurance is defined as a policy-based commercial insurance

which is more in line with the characteristics of its current mainstream mode

and is conducive to solving the problems in practice. The is applicable to serious disease insurance

and it is suggested that special provisions should be made in the Insurance Law. And it is also suggested that the should be formulated to provide the institutional basis for serious disease insurance.