The Gd₂O₂S:Tb scintillation ceramics is extensively used for neutron radiography and industrial non-destructive testing due to its bright green emission, high intrinsic conversion efficiency and high thermal neutron capture cross-section. However, the existence of Gd₂O₃ secondary phase in Gd₂O₂S ceramics impedes the scintillation property. In this work, The Gd₂O₂S:Tb precursors were synthesized in water-bath with H₂SO₄ and Gd₂O₃ as starting materials. Molar ratio of H₂SO₄ to Gd₂O₃ defined as n was adjusted to synthesize the precursors., which influence on the properties of the precursors and powders was studied. Chemical composition of the precursors changes with the increase of n, from 2Gd₂O₃·Gd₂(SO₄)₃·xH₂O (n<2.00) to Gd₂O₃·2Gd₂(SO₄)₃·xH₂O (2.25≤n≤2.75), and to Gd₂(SO₄)₃·8H₂O (n=3.00). After being calcined and reduced, all the powders form pure Gd₂O₂S phase. Morphology of the Gd₂O₂S:Tb powders is closely related to the phase composition of the precursor. Increasement of the XEL intensity shows two stages with n increase, corresponding to the phase transition of the precursor, respectively. The Gd₂O₂S:Tb scintillation ceramics were therefore fabricated by vacuum pre-sintering and HIP post-treatment. The ceramics were fabricated from the powders prepared with different n, achieving high relative density and XEL intensity, except the ceramics fabricated from the powders prepared with the n=2.00, 2.25, 2.50. The increase of n is beneficial to the removal of the Gd₂O₃ secondary phase from the Gd₂O₂S:Tb ceramics. This work provides a way for eliminating the secondary phase in Gd₂O₂S:Tb scintillation ceramics.