Tlie best fitting of relationship between genetic distance and heterosis was studied in wheat by modern regression analysis.The materials were composed of 10 varieties and their 45 combinatlons by diallel mating design.The results wer tested with the deta of maize,cotton and rice.The results showed that the best relationship between genetic dis-tance and heterosis for vield is Y=axbe(cx)(a,b>0;c<0)and the effects of outlier,numberof sampie and deta strecture of sample on the best fitting were discussde.