Abstract: Twenty一two wheat cultivars were used to investigate slow一rusting infected separately with Chinese race 1，2，3 of Puccinia recondita f, sp, tritici. The components of rust development, latent period, infection frequency， uredia size and uredospore production per square centimeter of leaf surface were related to each other and to the area under the disease progress curve (AuDPC)，mean rust severity of modified cob scale (heading and soft dough growth stage)and reduced yield per plot,as indicated by significant correlation coefficients (r=0.79一0,97), The reduction in yields of slow一rusting cultivars infected with puccinia recondita f, sp, tritici was significantly lower than that in the yields of fast一rusting cultivars, The multiple linear regression analysis to seven components indicated that latent period(%l)and mean rust severity(x:)were the major components reducing wheat yield(y).The equation estimating yield reduction was expressed to y=94,67一3,10x，+0.51xz(R=0,96) The latent period and mean rust severity compared to check cultivars may be used to estimate the slow一or f ast一rusting levels of wheat cultivars, The wheat cultivars were divided into slow一，midslow一，fast- and midfast一rusting types by hie.achical clustering methods according to the slow一rusting components.

Key words: Wheat leaf rust (Puccinia recondita f. sp. tritici), Slow-leaf rusting