The seismic wavelet, also known as the “far-field wavelet,” plays a crucial role in various stages of seismic data signal processing. Accurately obtaining the far-field wavelet has become a key challenge in seismic signal processing. Existing methods for obtaining the far-field wavelet have certain limitations, while methods based on direct waves to extract the source wavelet are complex and difficult to implement. In this study, an exploration of the characteristics of direct waves in marine seismic data reveals that the far-field wavelet is essentially the zero-offset direct wave. Building upon this understanding, we propose a simplified method to extract the far-field wavelet using direct waves from marine seismic data. The method involves simulating the impulse response of direct waves with different ghost wave delays to calculate the filter factors. This process facilitates the conversion of direct waves with variable offsets, referred to as “offset filtering”. Throughout the calculation process, the filter factors remain unaffected by the source signal, focusing solely on the time delay effect between the direct waves and the source ghost waves in seismic traces with different offsets. As a result, the entire calculation process demonstrates a high level of stability. By applying the obtained filter factors to the actual direct wave data in marine seismic records, we can obtain the corresponding far-field wavelet. Testing and processing of real seismic data validate the simplicity, practicality, and ability of this method to yield high-precision seismic wavelets.