A biotype of Scirpus planiculmis (S. planiculmis) resistant to Sufonylurea(SU) has inhabited in reclaimed paddy fields treated with SU herbicide-based mixtures, in the western part of Korea. The Fields have been cultivated for mono-cultural rice production with wet-direct seeding method and continuously treated with SU-based herbicide mixtures for thirteen years since 1990. The apparent SU resistance observed in S. planiculmis, was completely verified in the greenhouse tests. The growth reduction (GR50) values of 6 SU herbicides for SU-resistant biotypes were 47 to 100 times higher than those for SU-susceptible biotypes. The inhibition (I50) values of pyrazosulfuron-ethyl to acetolactate synthase (ALS) extracted from SU-resistant and -susceptible S. planiculmis were 409 nM and 0.8 nM, respectively. The I50 value of the resistant biotype was 511 times higher than that of the susceptible biotype. The germination and growth rate of corm and seed from SU resistant S. planiculmis under growth chamber increased with the rising temperature, more prominently in corm than seed. In the interspecific competition according to SU resistance S. planiculmis density and constant the rice 3 plants under wet direct seeded rice, the growth of rice decreased with the increase of S. planiculmis density and significant differences were from 6 plants of S. planiculmis density. Among the several herbicides having mechanism of action different from SU herbicides;, benzobicyclon and primisulfan proved to have excellent controlling effects on the SU-resistant S. planiculmis in the pot and paddy rice field experiment. The SU-resistant S. planiculmis biotypes were controlled very effectively by systematic treatment of benzobicyclon and benzobicyclon-included herbicides at 3 days before as well as 12 days after rice transplantation in reclaimed paddy field. The 800ml of 41% aqueous suspension of glyphosate per 10 a was very effective to control SU-resistant S. planiculmis biotypes.