There is a set of oceanic island type alkaline basaltic pyroclastic rocks composed of debris and fine-grained pyroclastic materials in western Jiamusi terrain, Yilan area. These rocks resulted from low temperature and high pressure metamorphism during the closure process of the ancient oceanic basin between Jiamusi terrain and Songnen terrain, and formed a large number of sodium amphiboles in them. The sodium amphiboles in pyroclastic debris are distributed uniformly and non -directionally, and generally show zonal structure. The core is mainly crossite and the edge part is glaucophane. The sodium amphiboles in fine-grained pyroclastic materials are distributed directionally, composed exclusively of crossite. Temperature and pressure conditions for the formation of these sodium amphiboles are quite similar, with temperature between 300 and 350℃ and pressure about 0.7 GPa. Based on mineral composition of pyroclastic debris and finegrained pyroclastic debris, structure characteristics of sodium amphiboles and deformation characteristics of pyroclastic debris, it is inferred that the primary conditions for the formation of sodium amphiboles are low temperature and high pressure metamorphism and sufficient sodium source. Under the condition of sufficient sodium source, the kinds of sodium amphiboles have a direct relationship with oxygen fugacity in the system. Glaucophane and crossite were formed under low oxygen fugacity and high oxygen fugacity respectively. The formation of these sodium amphiboles is related to the collision between Jiamusi terrain and Songnen terrain and also to the later deformation style of rocks.