A comb-filter based on Mach-Zehnder interferometer (MZI) is experimentally fabricated by splicing a section of single mode twin-core fiber (TCF) between two single mode fibers (SMFs). The wavelength spacing between the adjacent transmission peaks of the transmission spectrum of the device versus wavelength, the length of the TCF and the effective index difference between the two cores are analyzed. When a wavelength is chosen, the wavelength spacing between the adjacent transmission peaks is proportional to the square of the wavelength and inversely proportional to the product of length of the TCF and the effective index difference between the two cores. The insertion loss, the flatness of the transmission spectra and the extinction ratio of the fabricated comb-filters are tested and analyzed. The insertion loss of the device decreases effectively by tapering the splicing regions between the SMFs and TCF. The device with insertion loss about 7 dB is obtained and comb-filter with extinction ratio about 13 dB are obtained. The comb-filter with maximum peak power difference as low as 1.59 dB is also obtained. This device is simple and compatible.