The arrests were made by the forest department and the Special Task Force (STF) set up to check wildlife crimes in the state.
An official said the poachers, Miraj Ali, Bhaiti Ingty, Gyas Uddin and Abu Siddeque, were involved in a case of poaching of an one-horned rhino in the park in 2015.
A .303 rifle, some ammunition and a silencer were recovered from them.
Four park staffers were recently arrested for their involvement in the poaching network.
Poachers have so far killed eight one-horned rhinos at the Kaziranga National Park this year.