Parthenium hysetrophorus has been quickly spreading weed in different parts of Ethiopia (Javari and Ritz, 2012). And enormous losses to cattle health and human health decrease quality and quantity of milk products and suffer allergic skin, asthmatic reactions in the Parthenium weed infested areas and in addition decrease crop and range land production have been observed. The study was concerned on assessing the perception of farmers that live in Damot gale woreda, Wolaitasodo, Ethiopia on the effect of parthenium hysterophorus on grazing land and dairy products. A cross sectional study was carried out to assess the perception of farmers and primary data was collected using semi structured interview questions and through direct observation on the field of study area.50 randomly selected respondents were participated of this (60%) are male and the rest are female to answer the interview questions and the collected data were analyzed by using tables, percentages and finally expressed through full discussion. The study indicates that most people (44%) call this weed "bazoomatta", some other people (36%) knows its name as" worramatta "and (20%) are said sharafa. The weed seed is easily spread by animals, wind, water, vehicles, farmer's seed, machinery and seed has distributed in all terrestrial lands like around road side, grazing land, farming land and others. The Parthenium weed cause "enormous losses to cattle health and human health, decrease quality and quantity of milk products and causes allergic skin. The control method taken by the society was uprooting, burning and using chemical. The farmers identified the problem of Parthenium weed effect on milk quality (changes color, taste) and they said it reduces the marketability of milk and milk quantity. Due to a serious problem of Parthenium weed on the grazing land and dairy products the researcher suggested that farmers should work hard on controlling the distribution of p.weed into non infested areas and it should be up rooted before flowering and when the soil is moist enough to facilitate easy removal.