We report crystal growth, AC and DC magnetic susceptibilities [chi(T, H)], magnetization [M(T, H)], and heat capacity [C-P(T, H)] measurement results of GdSbTe single crystal. GdSbTe is isostructural to the confirmed nonmagnetic nodal-line semimetal ZrSiS of noncentrosymmetric tetragonal crystal structure in space group P4/nmm (No. 129), but it shows additional long-range antiferromagnetic spin ordering for the Gd spins of S = 7/2 below TN. Both chi(T, H) and CP(T, H) measurements confirm the existence of a long-range antiferromagnetic (AFM) spin ordering of Gd spins below T-N similar to 12 K, and an additional spin reorientation/recovery (sr) behavior is identified from the change of on-site spin anisotropy between T-sr1 similar to 7 and T-sr2 similar to 4 K. The anisotropic magnetic susceptibilities of chi(T, H) below TN clearly demonstrate that the AFM long-range spin ordering of GdSbTe has an easy axis parallel to the ab-plane direction. The field- and orientation-dependent magnetization of M(T, H) at 2 K shows two plateaus to indicate the spin-flop transition for H parallel to ab near similar to 2.1 T and a metamagnetic state near similar to 5.9 T having similar to 1/3 of the fully polarized magnetization by the applied field. The heat capacity measurement results yield Sommerfeld coefficient of gamma similar to 7.6(4) mJ/mol K-2 and theta(D) similar to 195(2) K being less than half of that for the nonmagnetic ZrSiS. A three-dimensional (3D) AFM spin structure is supported by the ab initio calculations for Gd having magnetic moment of 7.1 mu(B) and the calculated AFM band structure indicates that GdSbTe is a semimetal with bare density of states (0.36 states/eV fu) at the Fermi level, which is 10 times smaller than the measured one to suggest strong spin-fluctuation.