Abstract: This paper puts forward a risk assessment system of distribution network based on the utility theory to evaluate security of distribution network effectively. The probability of accident is acquired from historical data by using of statistical methods and the severity function is established based on the utility theory. Besides the line over\|load risk index and the bus low\|voltage risk index, this assessment system has also established the outage risk index of load buses according to the characteristics of the distribution network, which can assess the comprehensive risk of the distribution network. In addition, the relevant software is developed. In the end, taking the 10kV typical cable networks in Beijing certain district as example, the validity and rationality of this assessment system is proved.