Abstract: In the Chunguang block, by using the velocity and density of the sand and shale to construct the tuning wedge model, then perform the forward simulation, indicate the character of seismic response of the thin reservoir bed. Theoretic calculation and forward modeling prove that the tuning thickness of the thin reservoir bed in Shawan formation is about 8.7 m. When the thickness of reservoir bed is greater than 8.7 m, the top and base of the reservoir bed are generally calibrated at max trough and max peak, apparent thickness and true thickness are roughly or exactly equal. When the thickness of reservoir bed is less than 8.7 m, the calibrating location of the top and base of the reservoir bed will drift towards the Zero Phase, apparent thickness is markedly greater than the true thickness. There is a positive correlation between apparent thickness and true thickness. The conclusions are valuable for horizon calibration, tracing reservoir bed, predicting thickness of reservoir bed, and interpreting the amplitude attributes.