Abstract: The exploitation of petroleum was began in Sep.1975 in Renqiu oil field, the fluid injected to deep well from the end of 1976.In 1977, tho frequency of earthquakes was increased in the region of the oil field, and the swarm of small earthquakes occurred in 1978.Subsequently, two earthquakes with Ms>3.0 oceurred in 1979.Until Sep.1981, 52 earthquakes had been recorded.#br#In this paper, the method of conformal mapping was used and according to the data of fluid injection and oil exploitation the velocity of underground fluid flow in the group of Wumi mountain oil deposite was calculated.Thus the underground condition of fluid flow in this region could be inversed, and the relaton between injection-oil-exploitation and earthquakes was expressed.