The Linze earthquake swarm in Gansu province in Jun. 2004 are relocated using the double-difference earthquake location genetic algorithm, the seismogenic structure is discussed with the data of geological structure. The results show that the distribution of hypocenters stretchs along the north edge of Yumushan fault in NNW direction, the focus depths of the earthquake swarm are mainly distributed in 10-25 km, and the average is 16.3 km. The seismogenic structure is the east section of the fault, whose strike is NNW, the dip direction is SW, and the dip is about 60°.