Both root knot morphology and its huge cell number and size depend on the interacting parties between plants and its parasite nematodes Meloidogyne spp..Based on comparing root knot's texture and growth,it is firstly proposed in this paper that plant root-knots are classified into two types:single root knot and multiple root knot,and the growth process of the host plant′s root-knot is divided into 4 periods,namely,induction,development,maturation and deterioration. Compounds from root-knot are greatly different from those of apical cells in root. These genes include cell cycle genes,mitotic cyclin genes,cell wall cleaving protease genes,cell membrane function genes and cell metabolism genes, which are closely linked to the texture and compounds of plant root-knot caused by Meloidogyne spp..