Medical insurance for serious illness can be deducted before personal income tax. The coverage of serious illness insurance should be connected with urban residents' medical insurance and the new rural cooperative medical system. The medical insurance for urban residents and the new rural cooperative medical system should provide basic medical security according to the policy. On this basis, the major illness insurance mainly guarantees the eligible medical expenses of urban residents compensated by medical insurance and the new rural cooperative medical system when the insured (co-insured) is seriously ill and the medical expenses are high. High medical expenses can be judged by the fact that the accumulated annual compliance medical expenses of individuals exceed the annual per capita disposable income of urban residents and the annual per capita net income of rural residents announced by local statistical departments, and the specific amount is determined by local governments.