The invention provides a nitrogen making machine with a three-tower structure, which has reasonable structure and high efficacy. The nitrogen making machine is provided with a tower A, a tower B and a tower C, wherein the bottom of the tower A is provided with a valve 1, a valve 4 and a valve 7 in parallel; the bottom of the tower B is provided with a valve 2, a valve 5 and a valve 8 in parallel,and the bottom of the tower C is provided with a valve 3, a valve 6 and a valve 9; the middle parts of the tower A, the tower B and the tower C are respectively externally connected with a valve 10, a valve 11 and a valve 12; the top of the tower A is provided with a valve 13 and a valve 16 in parallel, the top of the tower B is provided with a valve 14 and a valve 17 in parallel, and the top of the tower C is provided with a valve 15 he a valve 18 in parallel; the other ends of the valve 13, the valve 14 and the valve 15 are connected with a pipe 5, the other ends of the valve 16, the valve 17 and the valve 18 are connected with a pipe 6; the tops of the tower A, the tower B and the tower C are respectively connected with a check valve 1, a check valve 2 and a check valve 3 and the otherends of the check valve 1, the check valve 2 and the check valve 3 are connected with a pipe 7; and a pipe 2 is provided with an air inlet, and a pipe 3 and a pipe 4 are bypassed mutually. The invention is suitable for serving as oxygen manufacture equipment with larger flow requirement.