The growth mechanism of Si3 N4 made by self-propagating high temperature synthesis (SHS) was in-vestigated using a gas-releasing method. The intermediate growing morphology of the colummar β - Si3 N4 crys-tals by the vapor-liquid-solid (VLS) mechanism was viewed in the gas-released samples. The hquid phasereguired for the growth of β - Si3 N4 depends upon the oxygen containing impurities in the reaction product, butnot the metallic impurities in it, nor the oxygen impurity and water vapor in nitrogen. In the growth process, β- Si3 N4 precipitates continuously from the liquid phase and the oxgyen redistributes itself between the hquidand sohd phases so that the oxygen content in liquid phase gradually decreases and can not be conpensated andthus the β -Si3N4 crystals grow into short columns. Increasing the oxygen content in the reaction product sti-malates to obtain β - Si3N4 columns with high height to diameter ratios. Suitable amounts of oxygen and watervapor in nitrogen are beneficial to increase the ratio of ct to β - Si3 N4 phases in the product.%通过放气法观察到了短棒状β-Si3N4以气-液-固(VLS)机制生长的中间形态．以气-液-固机制生长的β-Si3N4所需的液相依赖于反应物中的含氧杂质，而非反应物中的金属杂质，或氮气中的杂质氧气和水蒸汽等．在生长过程中，液相不断析出β-Si3N4，氧需在液-固中重新分配，使得液相中的氧逐渐减少，并得不到补偿，所以β-Si3N4长成短棒状．增加反应物中的氧含量，可以得到高长径比的β-Si3N4．氮气中适量的杂质氧气和水蒸汽有利于提高产物中Si3N4的α相与β相的比例．
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