CO esterification to dimethyl carbonate (DMC) routes holds significant economic and environmental value. Nevertheless, industrial routes suffer from drawbacks, such as raw material methyl nitrite (MN) was decomposed into by-products dimethoxymethane (DMM) and methyl formate (MF), which caused subsequent separation problem for the product/reactant mixture, which results in additional production cost. Previous studies have demonstrated that the acid site of NaY play an essential role in promoting the decomposition of MN. Herein, a series of Na2HPO4 -modified Pd/NaY catalysts were prepared to solve these problems. The results indicated that the introduction of Na2HPO4 increased the DMC selectivity (from 55% to 83%) and decreased the by-products selectivity [DMM (from 22% to 10%), MF (from 23% to 7%)] of Pd/PNaY-12 significantly. Based on the results of Py-IR, the amounts of Lewis acidic sites decreased, and NH3-TPD analysis shown that the amounts of weak acid sites (from 0.33 mmol/g to 0.14 mmol/g) and medium strong acid sites (from 0.46 mmol/g to 0.10 mmol/g) also reduced obviously. The outstanding performance should be attributed to the fact that the important intermediate *COOCH3 was more readily obtained after Na2HPO4 was incorporated. This work provides a convenient strategy for developing catalysts with high selectivity and low by-products.