Outdoor experiments of down-looking inverse synthetic aperture imaging lidar at 1.8 km and 3.4 km are processed. A nonlinear correction algorithm is given under the remote imaging mode, in which the phase delay cannot be neglected. In the experiment, the targets are pyramids put in the unmanned aerial vehicles and the unmanned aerial vehicles with retro-reflective material. The images of pyramids in different imaging distances and the unmanned aerial vehicles at 1.8 km are obtained through the range bin alignment algorithm in the orthogonal direction and phase compensation algorithm in the azimuthal direction. The two-dimensional resolutions reach 7.2 mm×5.8 mm at 1.8 km and 12.7 mm×9.2 mm at 3.4 km.