A method for detecting small and weak damaged targets based on Neighborhood Vector PCA (NVPCA) image enhancement was proposed. The main idea is that each pixel and its 8 neighborhood pixels in the damaged image are treated as a column vector to participate in the operation. All column vectors generated by each pixel will construct a 9-dimensional data cube. After PCA transformation, the correlation between the middle and neighborhood pixels is eliminated, so that the main information of the 9-dimensional data cube will be set in the first dimension, and the transformed first dimension data is NVPCA image. When the NVPCA image is processed again by LCM method, a better image enhancement effect is obtained. In addition, the region growth method is used to separate the damage target from background. The experimental results show that the method can detect the damage target with the size of 1 pixel and located in local bright area, and meet the requirement of on-line optical damage detection system for the accuracy of the damage target.