A phytochemical analysis of Avicennia marina has been investigated by GC-MS. Avicennia marina leaves, seeds, flowers, stems indicate the presence of, steroids, tannins, glycosides, carbohydrates saponnins, sterols, terpenoids and phenols. The Avicennia marina revealed the presence of active medicinal constituents by GC-MS. This study also helped to identify the formula and structure of biomolecular therapy which can be used as drugs. Avicennia marina was tested for their mosquitocidal activities. The toxicities were examined against the lab. Strain of 3rd instar larvae of Culex pipiens. The results showed that extracts of seeds and leaves of Avicennia marina were more efficient than other parts against third instar larvae of Culex pipiens mosquito. In view of these results, the purified active compounds from the most effective samples found in our studies could be effective in killing mosquito larvae or repelling adult female mosquitoes in an economical and safe manner.