Series of new benzimidazole derivatives have been prepared starting with synthesis of 2-(6-bromo-2-naphthyl)-1Hbenzimidazole by using ortho-phenyl diamine and 6-bromo-2-naphthoic acid. The compounds were further alkylated and acylated. The acetylene linkage was incorporated by reacting 6-ethynyl-4,4-dimethylthiochromanwith2-(6- bromo-2-naphthyl)-1H-benzimidazolevia Sonogashira coupling resulted2-(6-((4,4-dimethylthio chroman-6- yl)ethynyl)naphthalen-2-yl)-1H-benzo[d]imidazole. The newer benzimidazole derivatives were alkylated and acylated to obtained library of newer compounds. All the compounds were characterized by IR, 1H NMR, 13CMR and Mass spectroscopies. All newly synthesized benzimidazole derivatives were subjected for anthelmintic activity. To study the Anthelmintic activity Indian earthworm (Pheretima posthuma) was used at the concentration 10 mg/ml and 20 mg/ml. Albendazole is used as reference standard. Overall study exhibited that all the compounds have moderate to excellent activity.