• ZrS 2 was prepared as a saturable absorber for generating passively mode-locked in an Er-doped fiber laser. • The optical wavelength of 1531 nm was obtained by 1250 mW high-power pump, which made the saturated absorber have a high damage threshold. • By changing the cavity length, the maximum monopulse energy obtained by mode-locked operation is 23.65 nJ. With high nonlinear effect and low band gap value, ZrS 2 is a promising material in photovoltaic application. In our work, a ZrS 2 -polyvinyl alcohol thin film modulator was successfully prepared by liquid phase exfoliation. The modulation depth of ZrS 2 saturable absorber is 6.3 % and its saturation intensity is 3.92 MW/cm2. Large energy mode-locked phenomenon was obtained in the Er-doped fiber laser with ZrS 2 as an optical modulator. When the pump power was 1250 mW, the center wavelength, pulse repetition rate, and maximum pulse energy of the large energy mode-locked were 1531 nm, 604.23 kHz, and 23.65 nJ, respectively. This experiment proves that ZrS 2 has excellent nonlinear absorption performance, also provides a reference for the future research of large energy mode-locked based on transition metal dihalogenateds. [ABSTRACT FROM AUTHOR]