Abstract: It is recently recognized that the ore mineral system is a complex dynamic system,and that the min-eralization is of a non-equilibrium and non-linear process.Based on this theoretic framework,the mineralization is primarily a physical process,and the mineral system is a fluid-driven geological sub-system.The magma system with small volume is also of a fluid-driven geological sub-system.Therefore,there exist instinct relations between the small intrusions and the endogenic mineral deposits,and revealing such relations is the key to practice the metallogenic theory in complex systems.Listing some common contradictions in the prevailing magmatic-hydrothermal theory,it is emphasized that the hypothesis of metallogeny by the small magmatic intrusion has important theoretical and practical significances.Based on the pattern of spatio-temporal structure of the magmatic system,the small intrusion can be divided into the un-rooted and rooted intrusions,and the later is further divided into the head intrusion and the channeling intrusion.Because the solubility of ore-forming metals in geofluids positively relates to the values of temperature and pressure,the giant ore deposits are generally associated with the un-rooted minor intrusion.In such a magmatic ore system,the transmagmatic fluids take place crucial roles for producing ore bodies.The magmatic fluid not only injects the ore-forming metals into the magma system,but also triggers the magma to ascend quickly,and causes contemporaneous partial melting at the different depth levels.These features determine that the small intrusions often occur as a swarm instead of in individual magmatic body.Due to rapid upwelling of the melt-fluid flow,the co-metallogenic local stress field in a ore field characterizes that the main compressional stress axis is located in the vertical direction,which further determines the spatial pattern of the small intrusions.Accordingly,the small intrusion swarm is an efficient and mappable perspective element.Therefore,it can be said that the theory of metallogeny by the small magmatic intrusion opens new windows for improving magma dynamics,and is one of targeting elements for the regional prognosis of mineral deposits and a milestone from which new departures in the economic geology would be started.