Applying self-focusing lens as a key device for optical sensor in fiber digital holographic system, one fiber carried the beam for illuminating the object and the others conveyed the reference beam to the CCD. The reflective wave scattered from the object surface was collected with a self-focusing lens to interfere with the reference beam on the CCD target.The lensless Fourier transform holograms thus formed were digitally recorded and the experimental results show that the reconstructed images and the interferogram can be evaluated for object deformation. It is shown that with the use of a self-focusing lens by its special imaginary property, the fiber system presented here can be used for measuring small areas of an object or objects difficult to access, while the whole setup is compact and more flexible.