In this paper,by the limitation of maximum risk measured by VaR,the optimal proportional reinsurance policy of an insurance company in the case of two risk independent businesses and two risk dependent businesses is discussed,with the allowance of insurance company to invest in capital market.It is concluded that the terminal wealth and the optimal retention ratio are relevant to the maximum risk,the mean value,and the variance of rate of return of underwriting and investment portfolio,and insurers can make...