The invention discloses a power failure fault location method of a distribution network based on an improved ant colony algorithm, which comprises the following steps: establishing an overall path matrix according to a distribution network topology; dividing the normal power supply user group into a negative ant colony and dividing the normal power supply user group into a negative ant colony; determining the forward information element matrix and the negative information element matrix are respectively determined according to the differentiated ant colony, driving a positive ant colony algorithm for the forward information element matrix, and driving a negative ant colony algorithm for the negative information element matrix, performing the target search separately and calculating the element values in each information element. All the ants have been judged as the termination condition, and the forward pheromone matrix and the negative pheromone matrix are added and combined to obtainthe total pheromone matrix. The maximum value of the elements in the total pheromone matrix is the power failure fault point. The power failure fault location method improves the speed and the accuracy of the fault location without increasing the hardware input cost, shortens the response time, reducing the cost, and improves the customer satisfaction and the system operation index.