A modulation method applicable to an Overlapped X Division Multiplexing, OvXDM, system, and comprising the following steps: generating an initial envelope waveform in a modulation domain based on design parameters; subtracting a tail length of the initial envelope waveform from a width of the initial envelope waveform in the modulation domain, to obtain a virtual cutoff width of the initial envelope waveform; dividing the virtual cutoff width of the initial envelope waveform by a first quantity of times of overlapped multiplexing, to obtain a modulation-domain shift interval; shifting the initial envelope waveform by the modulation-domain shift interval in the modulation domain based on the first quantity of times of overlapped multiplexing, to obtain offset envelope waveforms in the modulation domain; multiplying symbols in a to-be-modulated sequence by the offset envelope waveforms that are respectively corresponding to the symbols, to obtain modulated envelope waveforms in the modulation domain; and superimposing the modulated envelope waveforms in the modulation domain, to obtain a complex modulated envelope waveform in the modulation domain; the modulation method further comprising a step of determining the tail length of the initial envelope waveform which includes the following steps: converting an amplitude of the initial envelope waveform to a power in the modulation domain, comparing the power with a signal-to-noise ratio threshold of the system, and determining a modulation-domain part of the initial envelope waveform corresponding to the power that is smaller than the signal-to-noise ratio threshold as tailing. generating an initial envelope waveform in a modulation domain based on design parameters; subtracting a tail length of the initial envelope waveform from a width of the initial envelope waveform in the modulation domain, to obtain a virtual cutoff width of the initial envelope waveform; dividing the virtual cutoff width of the initial envelope waveform by a first quantity of times of overlapped multiplexing, to obtain a modulation-domain shift interval; shifting the initial envelope waveform by the modulation-domain shift interval in the modulation domain based on the first quantity of times of overlapped multiplexing, to obtain offset envelope waveforms in the modulation domain; multiplying symbols in a to-be-modulated sequence by the offset envelope waveforms that are respectively corresponding to the symbols, to obtain modulated envelope waveforms in the modulation domain; and superimposing the modulated envelope waveforms in the modulation domain, to obtain a complex modulated envelope waveform in the modulation domain; the modulation method further comprising a step of determining the tail length of the initial envelope waveform which includes the following steps: converting an amplitude of the initial envelope waveform to a power in the modulation domain, comparing the power with a signal-to-noise ratio threshold of the system, and determining a modulation-domain part of the initial envelope waveform corresponding to the power that is smaller than the signal-to-noise ratio threshold as tailing. converting an amplitude of the initial envelope waveform to a power in the modulation domain, comparing the power with a signal-to-noise ratio threshold of the system, and determining a modulation-domain part of the initial envelope waveform corresponding to the power that is smaller than the signal-to-noise ratio threshold as tailing.