The shift-multiplexing complex spectral domain optical coherence tomography (CSD-OCT) is presented according to the occurrence of high-resolution tomographic image near the virtual image of reference mirror. The method of shift-multiplexing CSD-OCT is experimentally demonstrated by using p/2 phase-shifting algorithm to remove complex conjugate image and by shifting detection position to improve the quality of tomographic image, detection depth and bandwidth utilization. The tomographic imaging for a target sample of five-layer cover slips is performed in different depth regions with this method. The tomographic imaging of the sample made of eight-layer cover slips is further carried out combining with lateral scanning. The tomographic images of the target object are clear and legible. The results show that the higher quality tomographic image of a target sample within its desired depth can be achieved by moving the virtual image of reference mirror to the specified depth of the sample. The CSDOCT system with shifting detection can effectively extend the detection range inside sample, perform tomographic imaging at the specified location and make full use of optical coherence tomography system′ s bandwidth. The tomographic image of an object in its depth-target area can be improved.