Describe the use of image processing to extract gas-liquid two-phase flow characteristics of the image gray-value method of texture,introduction of PCA to make the dimensionality reduction of the multi-dimensional gray-scale.Compute the two-phase volume fraction with single variable nonlinear fitting and multi-variable support vector machine regression.After statistical analysis of a large number of measurement samples,get the empirical formula to strike a volume fraction with the first principal component measurements and the first,second and third principal component of measured values.compare to the true values of volume fraction,The results show that:The gray-scale of flow image and volume fraction have a good correlation,the single variable method is applied to calculate the low rate,and the multi-variable method is applied to calculate the high rate.The article propose a new idea for calculating of the volume fraction.