Perovskite light-emitting diodes (PeLEDs) have emerged as a promising candidate for next-generation displays owing to their excellent luminescent properties and low cost. However, the development of deep blue PeLEDs has been hindered compared to red and green emission devices, largely due to the challenge of an unstable spectrum. In this work, we present a method for achieving spectral stabilization by using the organic ligand dipotassium 7-hydroxynaphthalene-1,3-disulphonate (G SALT). Combined with experimental results, we confirmed that the multiple interactions between G SALT and perovskite components played an important role in rearranging phase distribution and enhancing spectral stability. The fabricated deep blue PeLEDs demonstrated electroluminescence (EL) peak at 456 nm with Commission Internationale de I’Eclairage (CIE) coordinates of (0.149, 0.063), meeting well with the Rec.2020 standard. Meanwhile, the peak external quantum efficiency (EQE) of 2.5% accompanied by the maximum luminance (L_max) of 969.7 cd/m² was achieved. The T₅₀ lifetime was prolonged to 10 min under a constant current density of 12 mA/cm², and there was no significant spectral shift in the EL spectra at high driving voltages ranging from 3.5 to 6.5 V. Furthermore, the films demonstrated stable photoluminescence spectra when subjected to ultraviolet excitation at 365 nm and continuous heating at 65 °C. This study confirms the active role of organic compound ligands in quasi-two-dimensional (quasi-2D) perovskites and provides a new approach for developing stable ligands for the luminescent layer of perovskites in the future.