Abstract: Distributed acoustic sensing (DAS) has become an increasingly important tool in seismic exploration due to its high resolution, efficient data acquisition, and long-term monitoring capabilities. Unlike conventional geophones that measure particle velocity, DAS detects phase changes in backscattered light and reflects axial strain responses along the optical fiber. Based on elastic wave theory, DAS forward modeling was conducted to investigate the conversion between DAS data and equivalent geophone data. A conversion method was proposed for seismic waves with a single constant apparent velocity. The influence of wave incidence angle and fiber helical winding angle on the DAS strain response was derived theoretically. Wavefield simulations under various velocity models generated both DAS and geophone records, enabling a comparative analysis of seismic characteristics. The findings reveal that: ① DAS is highly sensitive to axial strain, and its response to different wave types at varying incidence angles significantly differs from that of geophones. ② The polarity of DAS records is independent of seismic wave propagation direction and is determined solely by whether the fiber is elongated or shortened within the gauge length. ③ When the fiber is helically wound at approximately 35.3°, the P-wave strain response remains nearly uniform across all incidence angles, while the S-wave response is almost negligible. ④ DAS forward modeling effectively analyzes and predicts reservoir dynamics at different production stages, providing precise guidance for optimizing oil and gas extraction strategies.These results not only validate the effectiveness of DAS forward modeling but also offer insights into optimizing DAS sensitivity through fiber geometric design, thereby enhancing the application of DAS technology in seismic exploration.