The invention provides a stratum trap depicting method and system. The stratum trap depicting method comprises the steps that an identifiable inclined stratum, a tuning point corresponding to the identifiable inclined stratum and a layer leveling target layer are acquired; wherein the tuning point comprises an amplitude maximum value point capable of identifying the inclined stratum or an amplitude minimum value point capable of identifying the inclined stratum; the identifiable inclined formation extension is enabled to be intersected with the layer leveling target layer to generate a formation inclination angle and a sharp extinguishing point; a stratum trap boundary is calculated and generated according to the stratum tilt angle and the acquired tuning thickness corresponding to the tuning point and a triangular law; and description is performed according to the stratum trap boundary to generate the stratum trap. According to the method, the stratum trap boundary is accurately depicted by quantitatively calculating the tuning thickness, the stratum inclination angle and the cupping point, and the method has the beneficial effects of improving the accuracy and the calculation efficiency of stratum trap boundary depiction.