Cynanchum acutum, as an alien weed, has been invaded in pistachio orchard of Aran and Bidgol, north of Esfehan province. During 2009 growing season, life cycle of this weed, from germination up to seed formation, was investigated. Seedlings originated from under ground organs were emerged from early March and maximized in mid of March. Where as, seedlings grown from seeds were emerged from mid of April, maximized in early May and continued up to end of this month. The most originated seedlings from underground organs germinated and emerged from 10-19 cm depth of soil, where as, for that of originated seedlings from seeds this was 1-9 cm depth. The later seedlings didn't attach the pistachio trees and didn't produce flower during this growing season.