A new type of diffractive optical bar code (DOBC), which is different from the general bar code (GBC) and the hidden bar code (HBC) formed by CGH methods or grating modulated method, is proposed in this paper. Instead of reading bar code directly, the code information can be obtained from the first diffraction order of the bar code. The diffraction of the conventional HBC made by other techniques need to be focalized by a lens in its focal plane. By using Fresnel zone plate′s focusing function, and combining the HBC with Fresnel zone plate, a new type of HBC which has self focusing function is generated. The feasibility of the LHBC is proved by the experiments, confirming that the proposed HBC can be read more easily and has better performance than the HBC.