Laser active imaging systems are usually used in important region surveillance and dangerous target identification. However, the photoelectric imaging detector in the imaging systems is easy to be disturbed from opponents and this leads to errors of the recognition. In practice, the laser power and the spot position change momentarily and this leads to different laser-dazzling effects in every frame. Therefore, dynamic assessments of laser-dazzling effects must be better understood. A new no-reference dynamic feature metric (DFM) assessment algorithm based on the character of the laser spot and image feature is proposed. The features from accelerated segment test (FAST) algorithm is used to extract feature points of the target image and disturbed image. The target area is obtained via feature-point matching, and the characteristic of the laser spot reflects the image quality through the saturated pixel number and spot position in the target area. After that, the distribution of the feature points, edges and edge definition reflect the varieties of the image feature. The normalized DFM is obtained via product of the five factors above. The luminance imaging experiment is performed for the targets by utilizing the laser active imaging system. In the experiment, the disturbed images of different disturbing powers and different spot positions are obtained. The proposed DFM algorithm is used to evaluate the newly obtained laser-dazzling images, and the results show that the DFM gives a more reasonable evaluation result for different laser-dazzling images. The evaluation results reflect the invalidation of the target identification algorithm objectively.