The invasive species are one of the major threats to native plant diversity. Invasive plant species have dominated the fallow lands in Dimoria Tribal Belt of Assam state. The present paper gives an account of the phytosociology of the invasive species found growing on the fallow lands along the roadside of National Highway No. 37 and changes in its soil fertility status. Phytosociological parameters like density, abundance, and frequency of the species were collected by laying 3x3 m quadrates in the selected area. The soil quality indicators namely temperature, texture, bulk density, moisture content, p^H, organic matter, nitrate, phosphorus, and potassium were investigated under the five invaded sites with nearby forest vegetation as control. A total of 6 invasive plant species belonging to 3 families were recorded during the study period. The study revealed low soil quality status under the invaded sites as compared with the control. It is, therefore, necessary to check the invasion of these species through various measures.