Abstract: Due to its non-contact, no coupling agent, fast and high resolution nature, laser ultrasonic technology has great potential in the detection of defects of anisotropic carbon fiber braided composites. In this paper, the finite element method was used to analyze the effect of the excitation position and braided structure on the ultrasonic signal excited by the laser point source, also the propagation law and energy distribution characteristics of the elastic wave inside the material were obtained. A non-contact laser ultrasonic C-scan imaging system was built based on a 1 MHz air-coupled transducer, and the experiments of near-surface micro structure and internal defect detection in plain and satin carbon fiber braided composites were carried out. The experimental results have shown that the spatial distribution characteristics of the near-surface resin capsule, carbon fiber bundle shape, orientation, size and internal defects and so on in the carbon fiber braided composites can be observed with high resolution by employing the laser air-coupled ultrasonic imaging technique. It provides an effective method of the micro structure characterization and defect detection for the aerospace composites.