The Qulong copper porphyry deposit discovered in recent years is likely to develop into a superlarge copper porphyry deposit. The ore district has abundant surface water. There is a malachite precipitation zone several kilometers in length along the lower reach of the main water system in the ore district. This paper has discussed the main factors controlling the accumulation of malachite, the variation of element content in the water system before and after the rainy season and the indication role of hydrogeochemical anomalies in determining the position of the ore deposit and the perspective target area.