The Hongshangou porphyry copper-gold deposit is a typical deposit in the Hongshan polymetallic metallogenic area. It is located in the Wu'an depression of Shanxi fault uplift in the southern margin of the central North China Craton. The ore body mainly occurs in the Hongshan syenite porphyry. Muscovite and chlorite are well developed in the mineralization center and periphery. In order to discuss the diagenesis and mineralization significance of muscovite and chlorite in Hongshangou copper-gold deposit, electron probe microanalysis (EPMA) was used to analyze muscovite and chlorite in different occurrences and metallogenic stages of the deposit. The results show that the distribution characteristics of chlorite in the mining area can be divided into three categories: chlorite associated with metal minerals (Chl-1), chlorite altered from hornblende (Chl-2) and chlorite altered from biotite (Chl-3). The three chlorites are all Fe chlorites, indicating that they were formed in a reducing environment. The replacement of Fe to Mg and the replacement of Si to Al^Ⅳ in the structure indicate that the formation of chlorites is affected by Fe- and Mg-rich ore-forming fluids. The formation temperature of chlorite calculated by geological thermometer is between 112~272℃, which belongs to the range of medium-low temperature hydrothermal alteration, LA-ICP-MS results show that the completely altered chlorite is richer in Cu, Sn, Rb, Zn, Ti, Li, Sr, V, Co, Ni and Sn. Muscovite mainly includes primary muscovite (Ms-1) and secondary muscovite (Ms-2), which belong to ordinary muscovite and polysilicic muscovite respectively. The muscovite closely related to mineralization has the characteristics of high Si, Fe and low Al, LA-ICP-MS results show that the muscovite formed in the reducing environment is richer in V and W than the muscovite formed in the oxidizing environment, suggesting the mixing of meteoric water in the later stage of the fluid. Based on the research results of this paper, the ore-forming fluid of Hongshangou copper-gold deposit is acidic in the early stage and gradually changes to neutral in the later stage. The ore-forming environment of copper-gold deposit is near neutral and reduced medium-low temperature environment. The ore-forming fluid is rich in Fe, Mg and poor in Si.