A novel approach to saturable absorber (SA) formation is presented by taking advantage of the mode coupling property of excessively tilted fiber grating (Ex-TFG). Stable mode-locked operation can be conveniently achieved based on the interaction between Ex-TFG coupled light and deposited ferroferric-oxide (Fe3O4) nanoparticles. The central wavelength, bandwidth and single pulse duration of the output are 1595 nm, 4.05 nm, and 912 fs. respectively. The fiber laser exhibits good long-term stability-with signal-to-noise ratio (SNR) of 67 dB. For the first time, to the best of our knowledge. Ex-TFG based Fe3O4 SA for mode-locked fiber laser is demonstrated. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement