In order to establish a simple and easy method to evaluate pathogenicity of Radopholus similis in laboratory， and to determine the pathogenetic difference of different populations， in this study， different populations of Jinfeng No.1 tomato were inoculated with different inoculation concentration and treatment time at （25±1） ℃ by using quartz sand culture. The nematode reproduction rate， root disease severity and plant growth were detected. Four different populations of female worms （HN6， SZ-FZ， GJ-LY323 and DBSR） were inoculated with 50， 100， 150 and 200 worms per plant to 30-day-old plants. After 9， 16， 23 and 30 days of inoculation， it was found that R. similis developed， propagated， and mainly infected the cortical cells of tomato root system. The pathogenicity on tomato was different with different inoculation dose and inoculation time. The reproduction rate of nematodes and the root disease severity increased with the increase of inoculation amount and time， while plant growth decreased. After inoculation with 150 nematodes per plant for 23 days， the most significant differences were observed in each index， which could distinguish the pathogenicity difference among different populations. Eight populations of R. similis were inoculated to 30-day tomato with 150 nematodes per plant for 23 days， and it was found that the pathogenicity of eight populations was in order of SZ-SWK>HaiN-YJ> HL-XY>SZ-FZ≥GJ-LY323>DBSR>HN6>ML-HG. The results showed that tomato was a good host for R. similis， and pathogenicity of different populations can be evaluated by inoculating 30-day-old tomato with 150 nematode per plant indoors for 23 days and analyzing three indexes of nematode reproduction rate， root disease severity and plant growth.