Based on different symptoms on pest damaged cotton leaf including cotton aphid, cotton spider mites, cotton plant bugs, cotton leafworm and whitefly, the recognition system of pest damage for cotton leaf was presented. After collecting cotton images, the mottling areas with cotton spider mites, cotton plant bugs and whitefly were segmented by Otsu method in 2G—R—B color space. The mean value, variance value and skewness value of mottling areas were extracted on the Rand (R+G+B)/3 bands as color features if mottling areas appear, and topological descriptors and Hu invariant moments were extracted as shape features. Two layers dualtree complex wavelet was used to evaluate the texture features of cotton leaf. A support vector machine (SVM) classifier with radial basis function were employed to classify cotton aphid, cotton spider mites, cotton plant bugs, cotton leafworm, whitefly and normal cotton leaf. Experiment results showed that the classification accuracy was 88.1% when σwas 3.