The study takes the HER-2 positive breast cancer as example to calculate the medical burden of patients after the implementation of Jiangsu Province’s serious illness medicines policy, and it evaluates the implementation effect of serious illness medicines project according to the “catastrophic health expenditure” which is defined by WHO. The result shows that the policy could reduce the patients’ financial burdens and the probability of catastrophic health expenditure. At the same time, compared to the situation before the implementation of this policy, though the absolute value of total expenditure by medical insurance fund rises every year, the growth rate of expenditure decreases gradually, which means that the policy doesn’t cause a big shock to the medical insurance fund.