Abstract: The exploitation of symbiotic nitrogen fixation of nin-leguminous has great potentiality in agricultural productive practice. Studies on the various types of symbiotic nitrogen fixation and their characteristics may provide some insight in extending the scope of symbiotic nitrogen fixation. The acetylene reducing aetivities of root nodules or leaf nodules of following plants, collected in' southern part of China, were detected by gaschromatography: 5 species of Elaeagnus, 6 spp. of Podoearpus, 2 spp. of Cycas, 1 sp. of Casuarina, 2 spp. of Pavetta and 4 spp. of Ardisid the results indicate that 5 species of Elaeagnus, 2 spp. of Cycas and 1 sp. of Casuarina have significant nitrogen fixing ability, among them the root nodulation and their acetylene reducing activities of Vietnam elaeagnus (Elaeagnus sp.) and Cycas siamensis Miq, so far have not been reported. High acetylene reducing activities are found in the root nodules of Elaeaguns. e. g. the activities of root nodules of Elaeagnus pungens Thunb. may reach as high as 0.19 n mole C2 H2 reduced/mg, f. w/min, comparable to that of the leguminous.