The crystallization process, precipitation sequence and structure of precipitated phases during heating metglass (Fe0.1Co0.55Ni0.35)78Si8B14 at normal and 20 kbar high pressures were examined by means of X-ray diffraction method. It was determined that both at normal and 20 kbar high pressures the crystallization will proceed in two stages corresponding to the primary and eutectic crystallization respectively. At normal pressure, fee-Co was observed on primary crystallization, while Ni31Si12 and (FeCoNi)3(SiB) compounds appeared in eutectic transition. With increasing temperature or prolonging of tempering, the (FeCoNi)3(SiB) compound transforms into the (FeCoNi)23B6 phase gradually. On the other hand, on heating the metglass at 20 kbar, in addition to the increasing in crystallization temperature, another compound Co2B appears. Besides, it has been found that high pressure will restrain the formation of (FeCoNi)23B6 phase.The influence of high pressure on the crystallization of metglass is discussed from point of view of thermodynamics and kinetics.