The polarizability tensor of magnetized plasma in frequency domain in laboratory coordinate system is gained by using the transfer matrix between the principal and the laboratory system, and then its exponential function form in time domain is derived by inverse Fourier transform. Combined with the semi-analytical recursive convolution (SARC) algorithm in digital signal process techniques, the SARC-finite-difference time-domain method applied to magnetized plasma subjected to an arbitrary direction of external dc magnetic field is derived. The co-polarized and cross-polarized backward radar scattering cross-section for a magnetized plasma sphere are obtained by the presented algorithm. The computed results indicate the correctness and feasibility of the method.