For active optical imaging applications where targets are irradiated by a laser beam, the backscattering characteristic influences the image quality. An outfield experimental investigation of kilometer scale was conducted in this study. Unmanned aerial vehicles with complex shapes and various surface materials were used as targets. Backscattered signals were obtained, while the targets were located at different attitudes and distances. Furthermore, the relationship between the amplitude of the backscattered signal and the target distance was deduced and summarized at close and far distances. The experimental results can be helpful in detecting complicated targets with laser illumination.