In this paper, the pressure dependence of the crystallization temperature Tx and the crystallization activation energy △EX of metglass (Fe0.1Co0.55Ni0.35)78Si8B14 werestudied by measuring the electrical resistivity in-situ under pressure up to 3 GPas. It was found that application of high pressure not linearly, even not monotonicaly riases the Tx, as usually described in literatures for pressure dependence of Tx in metglasses, but shows some local detours on Tx vs. P curve in a general rising tendency. △Ex shows same behaviour analogous to that of Tx as the pressure rises. An analytical discussion indicates that pressure promotes the nucleation process and restrains the diffusional growing up of the crystallized nuclei on heating the metglass. As a combined result of the mutual contrary effects of pressure on nucleation activation energy a,nd diffusion activation energy, it gives rise the above non-monotonic rising behaviour of △Ex and Tx of the metglass studied. In addition to △Ex, pressure may also markedly affect the preexponential factor and produces a considerable change on crystallization temperature.