Abstract: A new method which can calculate the whole swath Doppler parameters of space-borne SAR(synthetic aperture radar) was presented. The method, based on space coordinate transformation, made the satellite position and velocity as references. Using the space geometric model and the coordinate transformation, a quartic equation between the slant range and the look angle was founded. After solving the equation, the look angle value was got, and the Doppler parameters were then calculated. The simulation results show that the calculation precision of the method can reach below 0.02Hz(Doppler centroid) and 2×10^-4Hz/s(Doppler rate) with no satellite position and velocity error. The precision can reach below 0.8Hz(Doppler centroid) and 0.07Hz/s(Doppler rate) even if there are measurement errors in satellite position (300m) and velocity (0.3m/s). This method is suitable for both single SAR and distributed SAR Doppler parameters precision calculations.