High peak-to-average power ratio (PAPR) and spectral leakage are two main problems of orthogonal frequency division multiplexing (OFDM) systems. For alleviating the above problems, this paper proposes a joint model which efficiently suppresses both PAPR and spectral leakage, by combining serial peak cancellation (SPC) and time-domain N-continuous OFDM (TD-NC-OFDM) in an iterative way. Furthermore, we give an analytical expression of the proposed joint model to analyze the mutual effects between SPC and TD-NC-OFDM. Lastly, simulation results also support that the joint optimization model can obtain notable PAPR reduction and sidelobe suppression performance with low implementation cost.