X-ray computed tomography (CT) has been widely applied as a powerful tool in both clinical medicine and industrial non-destructive test areas. With the development of flat panel detector in detection efficiency and anti-radiation property, the cone-beam CT based on the cone-beam source and the flat panel detector has been broadly used. However, the field of view of cone-beam CT is restricted by the hardware conditions such as detector size, and thereby the accessibility for larger size object applications is limited. In order to enlarge the field of view of cone-beam CT, a one-sided two-helical-scan single-slice-rebinning reconstruction algorithm is proposed. By performing one-sided two helical scans and normalizing the imaging geometries, two groups of helical cone-beam projections are recombined into one multi-slice parallel-beam projection, whose symmetrical feature is utilized to remove the transverse truncation in the data obtained, then the parallel-beam projection data covering the complete object cross-section is obtained, and thus the images are reconstructed by back projection. The experimental results show that the proposed algorithm can extend the field of view by 2.56 times with comparable imaging quality compared to the traditional algorithm.