Abstract: The experiment was conducted in greenhouse in Qingzhou, China from 2002 to 2003 to compare the diseases problems in the field and four fungi abundance in the rhizosphere between two tomato cultivars,the resist ant rootstock (Beaufort SIS-1,Lycopersicon lycopersicum×L.h irsutum) and non-resistant “Maofen-802”( Maofen,Lycopersicum esculentum Mill).After transplantation of “Maofen” and resistant rootstock grafted with “Maofen”,the dead rate of resistant rootstock seedlings in the field was 13.1%,significantly (T-test,P＜0.05)lower than 31.3%, that of “Maofen” plots. The principal diseases factors in volved tomato rhizoctonia rot (Rhizoctonia solani), tomato fern leaf (ToMV) and tomato damping off (Pythium aphanidermatum). In the late period of harvest (June 2003),the disease index of root-knot nematode in “Maofen” plots reached 80.0,significantly (P＜0.05) higher than 15.1 in the resistant rootstock plots. Similarly,the density of the second juvenile of Meloidogyne incognita in 100 grams fresh soil in “Maofen” plots was 657 individuals,significantly (P＜0.05) higher than 477 ones in resistant rootstock plots.In the harvest period, furthermore,it was found that beside Fusarium spp.in June and July 2003,the abundance (CFU per gram of fresh soil) of each of four fungi in the resistant rootstock rhizosphere was lower than that in “Maofen” plot.It is concluded,as compared with “Maofen”,the resistant rootstock shows a good resistance to soil born diseases such as rhizoctonia rot,damping off and root-knot nematode,and an obvious repression effect on the development of four fungi populations, Fusarium spp., Trichoderma spp.,Phytophthora spp.,Pythium spp.in the rhizosphere.