Synthetic aperture ladar is a coherent imaging ladar which uses relative motion of aperture to the target and signal processing to simulate apertures array to obtain high transverse resolution. Narrow line width single frequency fiber laser sour and coherent detection is employed; transmitted optical wave is modulated with chirped signal on amplitude, the received signal is compressed on length. Relative motion between ladar and target changes the phase of echo . Phase compensation and integration by correlation operation increases azimuth resolution. We bring forward a new work style: chirped signal on range dimension was modulated on optical signal amplitude, Doppler frequency shift on azimuth dimension changes optical wave phase (frequency) of echo , which is convenient for resolving coupling hazy problem between range and azimuth dimension. We report part experiment result : laser intensity was modulated with chirp RF, then range dimension compress for synthetic aperture ladar was realized.