The seislet-based POCS algorithm can be used to interpolate regularly missing traces, but requires a fairly accurate local slope estimation. The iterative slope estimation strategy may not always be successful, which will degrade the final interpolation performance. We propose a more stable way for calculating the local slope by using the velocity-slope transformation, which reduces the number of iterations needed in interpolation and can significantly improve the interpolation performance. Results from both synthetic and field data examples show that the proposed seislet-based POCS algorithm with one-step slope estimation can efficiently and effectively reconstruct the regularly missing traces.