To build up the resistant scale of rice cultivars against the false smut and to define relationship between the scale and rice yield loss, three main components of 24 cultivars relating to resistance against rice false smut were firstly analyzed by principal component analysis in this study. The relationship between percent yield loss (PYL) and the average diseased grains per panicle (ADGPP) was built by linear regression analysis. Based on the selected three components , 101 cultivars were clustered by the longest distance method with Euclidean distance. The result indicated that among the three components, ADGPP was a principal resistant component against rice false smut. The regression equation between PYL and ADGPP was y=2.862 4x+0.542 7 (P=0.000 1). Based on the above ADGPP, 101 cultivars were clustered into 6 groups by the above method at T=0.400 0. Thus 6 scales for evaluation of the rice cultivars against false smut in the field was built based on ADGPP, which agreed with Standard Evaluation System for Rice (SES) of International Rice Research Institute (IRRI), viz. scale 0, ADGPP=0.000 (highly resistant, HR); scale 1, ADGPP= 0.001 0.100 (resistant, R); scale 3,ADGPP=0.1010.410 (moderate resistant, MR); scale 5, ADGPP= 0.4111.010 (moderate susceptibility, MS); scale 7, ADGPP=1.0111.760, (susceptibility, S); scale 9, ADGPP≥1.761 (highly susceptibility, HS). The PYL were 0, 0.546%0.829%, 0.546%0.829%, 0.830%1.716%, 1.717%3.434%, 3.435%5.581% and above 5.582% for HR, R, MR , MS , S and HS scales respectively, which indicated resistant scales of rice cultivars and PYL were negatively related.