2,2',7,7'-Tetrakis(,-di--methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-OMeTAD), the most widely used hole transport material in high-efficiency perovskite solar cells (PSCs), still has serious defects, such as moisture absorption and poor long-term conductivity, which seriously restrict further improvement of the power conversion efficiency (PCE) and stability of the cell. Herein, to overcome these problems, inorganic salt PbSO(PbO) quantum dots (QDs) are incorporated into spiro-OMeTAD as the hole transport layer (HTL) for the first time. The incorporated PbSO(PbO) QDs significantly hinder the agglomeration of lithium bis(trifluoromethanesulfonyl)-imide and improve the long-term conductivity through the oxidative interaction between PbSO(PbO) QDs and spiro-OMeTAD and hydrophobicity of the HTL. Furthermore, the spiro-OMeTAD:PbSO(PbO) composite film can effectively passivate perovskite defects at the perovskite/HTL interface, resulting in suppressed interfacial recombination. As a result, the PSC based on the spiro-OMeTAD:PbSO(PbO) HTL shows an improved PCE of 22.66%, which is much higher than that (18.89%) of the control device. PbSO(PbO) also significantly improves the moisture stability for 50 days at room temperature (at RH ∼ 40-50%) without encapsulation. This work indicates that inorganic PbSO(PbO) QDs are crucial materials that can be employed as an additive in spiro-OMeTAD to enhance the efficiency and stability of PSCs.