Abstract: Megaalgal fossils are widely distributed over the world. These millimeter- to centimeter-sized bodies preserved as micrometer-thick carbonaceous films on bedding planes are generally sim-ple and their outlines are variable, ranging from theads and ribbon forms to regular and irregular,round and angulate, such as spheroids and discs, rectilinear or curvilinear maculation, ovate to spatulate, round to oblong, branched or unbranched and slender tubes or ribbons. Such carbona-ceous films were first reported from the Vendian of Russia in the mid-18th century. Chengjiang biota (530 Ma) is located at the Maotianshan(24°39'N, 102°57'E)of Chengjiang county, Yunnan province, China. Since it was reported by Chang and Hou (1985), many paleobiologists have successively gone there to investigate on the fossils. So far, a lot of animal fossils including 64 genera and 85 species were recognized (Luo et al., 1997). However, a few algal fossils reported from this biota, only two genera and two species Sinocylindra yunnanenesis and Fuxiananospira gyrata (Chen and Zhou, 1996, 1997). Recently, more than a thousand well preserved megaalgal fossils, at least 20 species, collected from Chengjiang biota. Morphologically, they can be assigned to Phaeophyta, Rhodophyta and Chiomphyta. Fortunately, an unbnmched whole tube with holdfast fossil morpho-logically resembles to living Enteromorpha appears. Based on the habit of living phaenphycean and the surrroundings of living Enteromorpha, Chengjiang biota was living in an environment of sea water.