The utility model provides a water deposit nitrogen cycle culture apparatus, including main culture tube, end cap and syringe. Main culture tube structure is both ends unclosed's cylindrical structure, and the both ends at main culture tube are arranged with the detachable mode to the end cap. Simple structure, easily operation, convenient to use to having reduced research cost, can maximum assurance having gathered normal position water deposit, the interference is little, and how many can go on simultaneously organize parallel controlled trial in the incubator, can guarantee that intraductalcleanness is clean according to the processing of the height and the later stage off -test deposit of experiment needs adjusted water body deposit.