Abstract: An imported NMR spectrometer is modified by applying computer control and data-processing technique. The operational temperature is changed from 20±1℃ to room temperature while its precision keeps unchanged. The hardware scheme is simple and reliable. Using known parameters of a standard sample, the software corrects the graduation unit of the system. Dynamic adjustable graduation unit is adopted for the algorithm. Known parametres of a standard sample are approached through double-identification and multi-repetition. The test results of other samples by using corrected graduation unit are satisfactory. Factors and regularities affecting the precision of the NMR spectrometer are also discussed.