Abstract: This paper is the result of research on the lithospheric mantle.ObjectiveIn terms of petrological and geochemical studies on a large number of mantle xenoliths, melt-peridotite reactions always occur in subcontinental lithospheric mantles, especially in the North China Craton (NCC). Based on the mineral metasomatic characteristics of mantle xenoliths and the related element geochemical signatures, the reaction between silicate melt and peridotite is the main type of melt-rock reaction within the NCC lithosphere mantle.However, the direct evidence of experimental petrography about the mechanism is insufficient. Methods In this contribution, natural olivine of harzburgite from Hebi, Henan province, and tonalite from Sandouping, Huangling, Hubei province were collected as starting material. The Si-rich melt-olivine reaction experiments were performed at conditions of 1 200~1 400°C, 1.0~1.5 GPa, on LC25-0300/50 piston-cylinder apparatus equipped at Key Laboratory of High-temperature and High-pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, which explored the reaction mechanism and kinetics of the melt-peridotite reaction. Results The main crystallized phase under experimental conditions is orthopyroxene, its En content ranges from 73 to 100 discriminated into enstatite.After reactions, the MgO content of reacted melts increased and linearly correlated with the temperature, while the contents of SiO₂, Al₂O₃ and K₂O decreased linearly with the increase in temperature.As the temperature increased, more forsterite was dissolved in the melts, and with more orthopyroxene generated, the SiO₂, Al₂O₃ and K₂O of melts decreased which changed the composition of the melts. Under the pressure of 1.0GPa, the temperature rises from 1 250°C to 1 350°C, the SiO₂, Al₂O₃, and K₂O in the residual melt decrease from 66.20%, 17.24% and 1.40% to 61.91%, 16.02%, and 1.28% respectively, however MgO in the residual melt increases from 3.93%to 8.26%.Under the pressure of 1.5 GPa, the temperature rises from 1 250°C to 1 400°C, the SiO₂, Al₂O₃ and K₂O in the residual melt decrease from 65.79%, 17.64% and 1.36% to 61.74%, 15.78%, and 1.23% respectively, however MgO in the residual melt increases from 3.11% to 7.07%. ConclusionsThe pressure has a much less influence on the chemical composition change or residual melts than the temperature. In all reactions between Si-rich melt and olivine, orthopyroxene was newly formed the experimental results also explain the composition of the peridotite in NCC and the phenomenon of the orthopyroxene veins in the peridotite, which can transform the lithosphere mantle from refractory into fertile.