Multifields space camera contains multiple independent system of optical imaging. In order to ensure overlapping of each imaging bands while space camera imaging continuously on the orbit, the groundtrack of field edge for camera need to be calculated accurately. Firstly, according to the characteristic that space camera imaging is perspective projection imaging, the strict mathematical relationship between image point and groundtrack point was deduction by combining space coordinate transformation with collinearity equation of centre projection. Then, illustrating by the case of double fields camera, the imaging bands behind different latitudes and attitudes were calculated. Finally, the fixing azimuth angle was calculated by restriction of bands overlapping. The optimal value is -0.28°. These two imaging bands of fields satisfied the requirement of overlapping, while satellite scrolling imaging between +40°and -40°. The method can be applied to other space camera of different types, and the groundtrack can be calculated at any attitudes.