The resources of nickel and platinum group element (PGE) are contributed by super-large scale magmatic Ni-PGE sulfide deposits in the world. In this paper， on the basis of the behaviors of Ni， Cu and PGE in the processes of partial melting， magma crystallization and sulfide segregation etc. mantle magmatic events， we summarized the types and scales of ore-forming magma， the gathering way of ore-forming metal elements， the controlling factors of sulfur saturation and the immiscibility of the sulfide liquid phase during the magmatism of Ni-Cu-PGE sulfide deposits， and discussed the role of volatiles in the transport and enrichment of ore-forming metals. It is concluded that the high degree of partial melting (i.e.， magma with high Mg content) in mantle is crucial to gather the huge amounts of Ni and PGE from mantle sulfide and olivine into ore-forming magma， and the sulfide segregation will form super-large scale Ni-PGE sulfide deposits in a large scale layered (or conduit) intrusion. It is inferred that the supercritical fluid (volatile) in mantle can carry and aggregate a large number of Ni-PGE metals from a large volume of mantle， and make a great contribution to the formation of Ni-PGE sulfide deposits. It is possible to be the metallogenic mechanism of magmatic Ni-PGE sulfide deposits by small mantle derived magma (i.e.， small intrusion).