Two strains of nitrogen-fixing cyanobacteria, Cylindrospermun licheniforme Kuetz. ex Born. et Flah and Nostoc calcicola Breb. ex Born. et Flah, were studied on their influence on growth and prpductivity of peanut (Arachis hypogaea L.) variety L14. The experiment consisted of 10 treatments, replicated thrice in a RCBD (randomized complete block design) on the sandy soil in Nghi Hai village (Cua Lo town, Nghe An province). Both C. licheniforme and N. calcicola expressed the positive effect on peanut. The suspension of 50 percent C. licheniforme or 75 percent N. calcicola used for foliar spraying every 7-day until the flowering stage significantly increased the physiological indexes of growth and yield of peanut. The economic yield was IIcreased by 12.31 percent and 12.97 percent, respectively.