The most agricultural concrete structures for the irrigation and drainage are exposed to the underwater condition at the irrigation period and they take the influence on very severe cold in the winter. Therefore, it is impossible to use repair materials used to the general concrete structures. The research need the development of the repair material for a performance enhance of the agricultural underwater concrete structures. This research evaluated the mechanical and durability performance of the latex modified repair mortar for underwater concrete structures which peformed the repair in the underwater according to the characteristic of the agricultural concrete structure. The latex modified repair mortar is a material that minimize the effect of the ecosystem, environment and the segregation. In this research, the construction condition of the latex modified repair mortar for agricultural concrete structures was considered and the test specimens made in the underwater condition. Test results was then compared with target performance and commercial repair mortar. Experimental test results indicated that the mechanical and durability performance of latex modified repair mortar for agricultural underwater concrete structure satisfied all target performance. Also, the latex modified repair mortar resulted in better repair performance than the commercial repair mortar.