Abstract: High α-phase silicon nitride bulk was prepared by direct nitridation method combined with high-energy ball milling. Taking silicon powder and α-Si₃N₄ diluents with different mass ratios as the raw material,the green block with different thicknesses were compressed,then the Si₃N₄ bulk materials were prepared by nitriding at 1350℃ for different times.The process factors for the synthesis of silicon nitride bulk materials through direct nitridation reaction of silicon blocks were investigated. The results show that when the silicon block with a thickness of 3 mm and 15% diluent (α-Si₃N₄) content is nitrided at 1350℃ for 3 h under a flowing nitrogen gas atmosphere,the nitridation effect is the best,and the products consist of three phases.The mass content of each phase is as follows:α-Si₃N₄(88.7%),β-Si₃N₄(10.2%),and Si(1.1%). The process successfully synthesizes silicon nitride bulk materials with a high α-phase content. The results of the study provide evidence for the efficient preparation of bulk silicon nitride with high α-phase content.