We have developed a fast detector calibration method, which is capable of calibration of monolithic crystal detectors fast and conveniently. This method could potentially be used to achieve the DOI calibration information of a thick detector. Compared with traditional calibration method, this calibration technique doesnt require a well-collimated pencil beams, and can calibrate a detector in reduced time with fan beams. After the collection of the calibration reference dataset, we propose a data-processing method called common-data subset (CDS) method to acquire the reference datasets as if they were acquired using a pencil beam or even as if there is a single-point light source scanning inside the scintillator. If using fan beams, only 2N scans (in x and y directions) are necessary to calibrate the whole detector surface instead of doing N2 scans using pencil gamma-ray beam. For calibration of the DOI information, 3N scans are necessary, within which the last set of N scans are done with slant beams. Monte-Carlo simulation has been done to support the feasibility of this method, which enables simple, fast and robust calibration for monolithic crystal detectors.