Abstract: La Yesca silver polymetallic deposit, located in the southeast of Madrid orogenic belt in Nayarit, Mexico, is a large Mn-Ag polymetallic deposit discovered in recent years. The deposit is occurred in the Cenozoic acid intermediate-intermediate pyroclastic rock formation, with shape, scale and occurrence of orebodies strictly controlled by Cenozoic magmatism and NW-trending faults. Three comprehensive anomalies are delineated by stream sediment survey, from two of which, industrial ore bodies are found by surface trenching and drilling verification. Through analysis of regional geological background, geological characteristics and ore-controlling factors of deposit, it is considered that the deposit is an epithermal Ag-Mn polymetallic one related to Cenozoic volcanic activity, and there is still great prospecting potential in the deep and periphery of the deposit, with the possibility of finding super-large epithermal Ag polymetallic deposit.