This paper discusses preliminarily the relationship between Terminal Precam-brian filamentous algae and their sedimentary environment in Hunjiang, Jilin.These filamentous algae found in different beds mostly belong to blue algae.Based on a study of the whole appearance of the filamentous algae and the abun-dance of their individuals, three types of filamentous algae are distinguished:mat--algae, isolated algae and transitional algae respectively. According to a studyof the ecology of modern filamentous algae and their sedimentary environmentand tbe method of analogy, the authors discuss the sedimentary environmentmodel of the Terminal Precambrian filamentous algae in the Hunjiang area,which accords with the analytical result of the environment of filamentous algae.Therefore, filamentous algae become one of indicators of facies.