Simple Sequence Repeats (SSR) marker was used to analyze genetic diversity of 20 samples of processing tomato for evaluation of genetic relationship. The results show that a total of 43 bands were scored from the 12 primers, which were screened out from 49 primers and demonstrated highly reproducible, clear and polymorphic bands. Among the obtained bands, 37 were polymorphic, accounting for 86% of the total. Analyzed by NTSYS2.2, the genetic similarity coefficient among the accessions ranged from 0.419 to 1.000, which indicated that genetic basis was relatively abundance among the 20 processing tomato resources. A dendrogram was constructed by UPGMA cluster method. The 20 samples of processing tomato were classified into 3 major groups, the materials that have a distant genetic relationship between major groups or sub-major groups, which may be used as elite materials for further genetic improvement in this species.