Selective technique of good breed er strain in Cypr carpio hoe-matoterus and C. carp was carried from 1986 to 1990. In heilongjlong commonearp,the interstrain selection was used. The parents were collected from lower Song-hua River，middle Nenjiang River and inghai Lake, and self-reproduction wasdone separately. Samples were observed randonly fromF，，the comparison of gro-wth of 1,2 and 3 year old was done in same pond or in different pond，instantane-otxs growth rate(IGRW )and relative growth rate(GW )were determined. The morpho-fogy and iso2ymes were studied too and ebvious differences of morphological andbiochemical genetics were found in three wild common carp strains,and the growthof Songhua River wild common carp is aver 10faster than the two others. So that anew strain was screened out. In mirror carp, the interstrain crossing and sequentselection were used. The crossing was done by the scattered mirror carp (selected30 years at Songpu Test Farm of our Institute) and the pure line mirror carp (in-troduced from West Germany in 1984).The comparison of growth hybrid Fl andits parents of 3 different ages was done in same pond or in different pond, andIGRw，GW,morphology,and isozymes were determined. The results are as follows:morphological character of Fl is in the middle of those of parents，mean heterozy-gosity of F₁, is zero, and growth of F₁, is over 20% faster than average of parents.