In this study, a delicious mixed mushroom sauce was developed using the rare mushroom Oudemansiella raphanipes and the common oyster mushroom Pleurotus ostreatus as raw materials. Using principal component analysis (PCA) and partial least squares-discrimination analysis (PLS-DA), the flavor changes of mixed mushroom sauces with different mixing ratios were examined as a function of cooking time. The results showed that at a cooking time of 4 min and a 4:6 mixing ratio between oyster mushroom and O. raphanipies, the umami taste of the mushroom sauce was the strongest (m/m). At a cooking time of 4-5 min and a 4:6 ratio, the aroma quality was the best. Fourteen compounds, including glutamate and geraniyl acetone, resulted in significant differences in the umami and aroma of the product at different cooking times. This study will provide a theoretical basis for improving the flavor quality of mixed mushroom sauce, and, more broadly, promote the development of the edible mushroom processing industry.