As an important next-generation photoelectric material, the controlled synthesis of two-dimensional molybdenum disulfide (2D MoS₂) with high uniformity is imperative. Traditional MoS₂ growth methods in the open space usually require a large amount of raw materials and have poor uniformity of growth results. In this paper, we report a space-confined method for uniformly growing large MoS₂ flakes on the SiO₂/Si substrate. As the precursor film coated on the bottom substrate is restricted in a small confined space between the top and bottom substrates separated by a small spacer, it is efficiently utilized, achieving large MoS₂ flakes with good uniformity on the top substrate. By further tuning the content of NaCl catalyst in the precursor, single-layer or multi-layer MoS₂ flakes can be obtained in a controlled manner, and well characterized by Raman, XPS, PL and AFM. The uniform distribution of Mo-containing species and its high concentration in the confined space, contributing to the efficient growth of uniform large MoS₂ flakes. This research will provide guidance for rational synthesis of 2D MoS₂ flakes on dielectric substrates.