Abstract: What achievements had the irrigation works obtained during the Great Leap Forward? Were there any errors or disadvantages? How should we evaluate these errors and disadvantages? These questions were disputed during the Great Leap Forward, and are still at variance in academic circle at present. Generally speaking, there are two viewpoints on the merits and defects of the irrigation works during the Great Leap Forward. One declares that the advantages of the irrigation works were greater than the disadvantages though errors and failures exist indeed, which is the mainstream in academic circle. The other one asserts that the loss of the irrigation works was greater than the gain and emphasizes the major mistakes and severe deficiency despite affirming the achievements. I think denying the achievements and emphasizing the defects blindly is not consonant with the historical facts; meanwhile, emphasizing excessively the merits and not affirming the disadvantages is not realistic, either take the irrigation works during the Great Leap Forward in mass, both merits and defects existed; the achievements were the main aspect and the errors were the secondary aspect; the achievements were great; while, the lessons were profound.