Phase retrieval of in line X-ray phase contrast computed tomography (IL-XPCT) with Born approximations is achieved by using images recorded at single sample-to-detector distance. Experiments are carried out at X-ray imaging and biomedical application beamline,by taking a phantom and a locust as the samples. After phase retrieval,much better IL-XPCT slices and three-dimensional rendered images are obtained. The results show that the potential application of the proposed method to three-dimensional non-destructive imaging of biological samples.