Abstract: Based on the discussion of the nature and work condition of geotextile, its negative effect on long-term stability and post-construction settlement in soft ground improvement of highway was analyzed. The stability might decrease due to its loss of long-term strength and reduction of modulus. The geotextile could also induce some harmful effect to the post-construction settlement due to its long-term deflection and relaxation. The results of test section in a highway show that the post-construction settlement increased by one layer of fabric can be ignored but the post-construction settlement increased by two layers of fabric may reach 40⁵0 mm.