Currently the risk assessment of operation environment for overhead transmission lines mainly based on complicated hazard identifying and risk assessment(HIRA)and the cumulative points methods. To simplify the histogram risk assessment of overhead transmission lines

a histogram risk assessment model of overhead transmission lines based on least squares support vector machines(LS-SVM)and principal component analysis(PCA)is developed. Firstly

through a statistical analysis of fault tripping

10 kinds of running environmental technology factors that endanger the safety of the overhead transmission and corresponding characteristics are obtained. Considering the complexity and workload of the actual data collection and risk assessment

PCA is used to reduce the dimension of factors to obtain characteristics factors. These are used as inputs of LS-SVM to build a risk assessment forecast model. Finally

an example based on a traditional assessment sample is given to show the accuracy of results of the training and assessment model can reach 95%.