Abstract: Underground in-situ exploiting of oil shale is a new method developed in recent years. The oil shale layer thickness in Northeast China is usually less than 10 m, so oil shale can be heated in horizontal wells. A method of electric heating in horizontal wells is developed. Using FLUENT software and in combination of self-developed FORTRAN program, the electric heating process was numerically simulated in horizontal well and vertical well, and the calculation results was compared. The change process of average temperature, oil production and thermal loss of oil shale with time was analyzed, and the power consumption during heating was calculated. The calculation result shows that the thermal loss of electric heating in horizontal well is less than that in vertical well, so this method can shorten the production time and reduce production cost.