We investigate the various roles of MgO in Fe-Ni-Mg catalytic system in the catalytic pyrolysis of pine needle biomass in a fixed bed reactor. And the change of productions was discussed to reveal the various roles of MgO at 750 degrees C. We found that in the presence of MgO, hydrogen content was enhanced. And the variation in the Mg/3 Fe 1 Ni mass ratios indicated that MgO could act as a promoter at 750 degrees C, and a catalyst at Mg/3 Fe 1 Ni ratio of <1, and >1, respectively. Moreover, the impact of temperature and heating rate for biomass pyrolysis with 3 Fe 1 Ni 0.4 Mg catalyst were studied. Firstly, as the temperature changed from 450 degrees C to 750 degrees C, hydrogen increases from 40.70 mL/g to 120.98 mL/g. Secondly, when the heating rate was 10 degrees C/min, the gas yield reached the maximum value of 34.27%. At the same time, the content of hydrogen product was also the maximum, 120.98 mL/g, a possible mechanism of biomass pyrolysis with Fe-Ni-Mg catalytic system is proposed. The surface characteristics of 3 Fe 1 Ni, 3 Fe 1 Ni 0.4 Mg and 3 Fe 1 Ni 4 Mg catalysts were analyzed with XRD, SEM, and TEM. XRD results indicated that Fe-Ni alloy was formed during high temperature, which contributed to the enhancement of hydrogen. These findings manifested that Fe-Ni-Mg catalyst can be used as low-cost catalyst to enhance hydrogen.