Abstract: The Xiajibaogou gold deposit is located in the central section of the Ergun block.Its geography location is about 15 km to the southeast of Jilalin town,Ergun city,Inner Mongolia Autonomous Region.The Ergun River (the boundary river between China and Russia)is located in its west about 10 km.There is the Jilalin large placer gold deposit nearby.Xiajibaogou gold deposit occurs in monzonite and is closely related to it.The monzonite is both host rock and mineralized rock.Hercynian granites are broadly distributed around the monzonite.NW-striking and NE-striking tensional fractures occur in the monzonite.The orebodies are controlled by the tensional fractures.Xiajibaogou gold deposit was formed in late Jurassic.Its Au-mineralization is mainly related to pyritization and arsenopyritization,other than silication.Au-mineralization occurred following the monzonite.The ore-forming matter probably came from depth.The ore is altered type.There are metallic minerals (pyrite,arsenopyrite etc.)and nonmetallic minerals(feldspar,sericite,muscovite,pyrophyllite,etc.)in the ore.A/NKC of the Xiajibaogou monzonite range from 1.43 to 1.85, ^efrom 3.13 to 7.28,Na₂O+K₂O from 8.78 to 10.9,ΣREE from 70.024×10^-6 to 228.97×10^-6, ^WEu from 0.480 to 0.683 and ΣCe/ΣY from 4.70 to 7.51.The ^WEu presents negative anomaly.The ΣCe/ΣY is larger,so the Xiajibaogou monzonite fractionation is better.The Xiajibaogou monzonite is high alkalinity and alkali-lime syntectite.Its sulfur isotope and rare earth element show some crustal mass mixed into it,suggesting that the Xiajibaogou monzonite be hysterogenetic substance.The application results of magnetic measurement and phytogeochemical method are obvious in the Xiajibaogou gold deposit.They have indicating significance on prospecting in Ergun region.