N-continuous orthogonal frequency division multiplexing (OFDM) is a promising sidelobe suppression technique by enhancing the continuity between adjacent symbols with higher-order derivatives. However, it has high computational complexity due to the large-scale matrix operations in frequency domain. In this paper, a low-complexity time-domain signal processing (TDSP) algorithm for N-continuous OFDM is proposed. Based on linear combination of basis vectors, it utilizes small-scale matrix operations to generate the coordinates to construct N-continuous OFDM signal. Simulation results approve that the proposed algorithm achieves dramatic complexity reduction with identical sidelobe suppression and BER performance compared to conventional frequency-domain processed N-continuous OFDM.