A novel miniature double-beam spectrum measurement system called double-beam miniature spectrometer is proposed based on twin-core fiber and 2-D CCD detector Czerny-Turner spectrometer. The advantage of the miniature spectrometer with small size and fast measurement and the superiority of the double-path spectrophotometer with double light paths are both presented. In this system, the light intensity of the light source is divided equally into two parts by the first two-core fiber. One part is considered as the reference light path, and the other is considered as the sample light path. Then the reference light and the sample light are transferred to the slit of the spectrometer by the second two-core fiber. The two cores of the second two-core fiber are distributed along the direction of the length of the slit (the direction of the non-dispersion). In order to avoid the overlapping and the crosstalk between the sample spectrum and the reference spectrum, astigmatism corrected cylindrical lens is added into the symmetrical crossed Czerny-Turner optical bench. The optical design software is used to optimize the system aberration. The ray tracing result shows that the imaging spectra of the reference path and the sample path can be clearly distinguished in the wavelength range of 300~800 nm. Eventually, the experimental prototype of the double-beam miniature spectrometer is manufactured and aligned. The sample spectrum and the reference spectrum can be displayed and measured simultaneously with the system. The design method of the double-beam miniature spectrometer is verified by the experiment. The light path of double beam, the characteristic of fiber connector and flexible configuration are realized in the double-beam miniature spectrometer.