Abstract: Acoustic time difference is a key parameter for evaluating reservoir physical properties and ground stress, which is irreplaceable especially in the fracturability evaluation. At present, shale reservoirs are mainly developed by horizontal wells. Due to the development of lamellation, there is a big difference in the measured value of acoustic time difference between horizontal wells and vertical wells, in which case a large error will occur when reservoir evaluation is performed using the originally measured acoustic curve. Based on the finite-difference time-domain algorithm, this paper constructs the acoustic time difference simulation algorithm under the conditions of highly-deviated wells/horizontal wells, and systematically simulates the acoustic logging response regularity under different relative deviation angles of the well and different acoustic anisotropy coefficients. When the well deviation angle is less than 20°, the time difference of deviated wells basically equals to that of vertical wells; when the formation acoustic anisotropy coefficient is greater than 0.04, there is a big difference in the acoustic time difference between deviated and vertical wells, which also increases with the increasing of acoustic anisotropy coefficients and well deviation angles. Under the time difference of longitudinal waves in different vertical directions, the change laws of acoustic time difference with acoustic anisotropy and relative well deviation angle are basically consistent on the whole, but the change range increases with the time difference in vertical direction. The relative value of the difference between time differences of deviated and vertical wells has an approximately sinusoidal function relationship with well deviation angle, which is irrelevant to the time difference in vertical direction. Based on the above simulation results, this paper establishes the correction method for acoustic time difference in horizontal wells under different acoustic anisotropy coefficients. Finally, the above methods are applied to actual horizontal wells, and a comparison is performed between the porosity calculated based on the corrected acoustic time difference and that calculated by neutron-density, from which it can be found that the both are basically coincident, and the corrected acoustic porosity is nearly consistent with the porosity of adjacent vertical wells in terms of peak values and distribution intervals; the acoustic anisotropy ratio calculated after correction is 1.18, and falls within the range of acoustic anisotropy ratio obtained by petrophysical experiment, i.e., 1.04~1.24, consistent with its major peak interval, i.e., 1.16~1.20. This reflects that the correction effect is good, and the acoustic time difference of horizontal shale wells can be corrected.