Abstract: Many geological facts show that pyrite is an important gold -hosting mi neral in gold deposits. Many geologists have studied the genesis of this phenome non in the past based on the geochemical properties of elements and adsorption e xperiments. In this paper, the genesis and characteristics of gold hosted by pyr ite is studied mainly in the light of mineral structures and properties as well as crystal growth of pyrite and native gold so as to comprehend this phenomenon further. 　　According to the statistical data of gold-hosting minerals from 102 gold deposi ts with different genetic types, there are more than 19 species of minerals cons idered as gold-hosting minerals, which include sulfides, oxides, silicates, car bonates and sulfates. Of these gold-hosting minerals, pyrite is the most common and most important gold-hosting mineral in gold deposits. The number of gold d eposits with pyrite as gold-hosting mineral is up to 98% of the total 102 gold deposits, and the number of gold deposits with pyrite as major gold-hosting min eral is about 85%. 　　The cause for pyrite to be a major gold-hosting mineral comprises three mineral ogical factors: the structural factor,nucleation factor and electrochemical fact or. The biatomic sulfur ［S2］2- in the crystal structure of pyrite may cause the reduction of Au+ and Au3+ to Au0 during the biatomic sulfur formtion. The crystal nucleation of native gold usually selects the pyrite surf ace as backing in order to decrease the energy barrier of crystal nucleation, be cause the arrangement of atoms in pyrite is closest to that in native gold. The electrochemical reaction caused by the thermoelectricity of pyrite may take plac e on the pyrite surface, which in turn may reduce the ionic gold to Au0 to cry stallize. 　　Analysis on the gold-hosting capacity of pyrite shows that the fine-grained,an hedral, cracked pyrites with higher contents of As and Sb, and with P-type the rmoelectricity have higher capacity of gold-hosting. The euhedral pyrites with {210}, step-face {100} and combined form also have higher capacity of gold-hos ting.