To effectively enhance the bandwidth range and imaging signal-to-noise ratio for inertial space observation, we propose a design method for the active scanning of long arc star sources using TDI cameras, based on the mapping function of star magnitude and optical multi-parameters. First, we construct a mapping function between TDI optical parameters and the limit detection star magnitude, grounded in the blackbody radiation energy density formula. Next, employing homogeneous coordinate transformation and the Euler axis optimal path planning method, we establish an imaging model for dynamic star source scanning with continuous compensation of inertial space satellites and payload. This achieves high signal-to-noise ratio imaging of dynamic star sources without tailing. Finally, leveraging the theory of parallel experiments, we build an experimental system consisting of a TDI camera and a dynamic star source simulator, conducting scanning imaging experiments and error analysis. Experimental results indicate that when the Euler angular rate of the body coordinate system relative to the inertial coordinate system is 8.5 (°)/s, the integration series is 96, the row frequency of the TDI camera is 1 kHz, and the imaging duration is 10 s, the imaging signal-to-noise ratio of the star map reaches a maximum of 7.325, and the solid angle of the scanning area is 5.423 2. The active scanning of long arc star sources by the inertial space TDI camera can achieve high signal-to-noise ratio imaging of star sources and significantly expand the observation range of imaging.