Field experiments were conducted from the second crop season of 2001 through the second crop season of 2002 on the paddy fields at Agriculture Experimental Station of National Chung Hsing University. To investigate effects of several weed control methods on quality of rice cultivar Tai-Keng in organic farming. Chemical and physical qualities of rice were investigated by laboratory analysis. Weed control measures had no significant effects on appearances of rice. The content of amylose and crude protein of rice were higher in the second crop than that in the first crop. Contents of crude protein in rice harvested from smoked rice hull and paper mulching plots were lower in the second crop of 2001. Contents of crude protein in rice harvested from soybean meal and rice bran treatments were higher in the second crop of 2002 than that from other treatments.