This research aims to evaluate the knowledge impact for the extension activities of the field irrigation development project in the ancient lands in Beni Suef and Nasser districts at Beni Suef Governorate. three villages were chosen, then simple random sample of 145 respondents was taken from them as excremental sample. Two villages, where the project was not implemented, and a control sample of 1% was chosen from them reached 50 respondents. Some statistical tools were used in analyzing the research data as: simple and multiple correlation coefficients, partial regression coefficient, “T" test, and coefficient of variation. The important results were: 96.5% from the experimental sample had a high degree of knowledge related to extension activities for the field irrigation development project (FIDP), while this percentage in the control sample was only 4%. It became clear that there were significant differences between the experimental and control samples in the degree of their familiarity with this knowledge based on the (T) value. That 96.5% of the experimental sample had high knowledge impact for the extension activities of the FIDP. The most important independent variables related to the knowledge impact of the extension activities of the FIDP were: opinion leadership, the advertising and publicity for the FIDP, participation in extension activities, attitude towards the FIDP, and participation in extension activities for the FIDP, and inversely with the respondent age. The independent variables included in the research together explain 24% of the variance in the dependent variable.