Abstract: The Ministry of Justice as the core authority handling criminal affairs,the specialization level of the Ministry’s officials，was able to take advantage of its powers and greatly affected the System of the whole country security. There were significant changes on many aspects within the Ministry after the Yongzheng and the early Qianlong reign period,including personnel arrangement such as the selection, investiture and accreditation of officials.After that,the officials’ entrance age was decreased, work time was prolonged.A combination of substitution and assignment made the officials divid into two classes.The ascending of officials was increasingly controlled by the chief officials in ministry. In older to be appreciated, the young officials tried a case during the day, and stuied the legal knowledge in the night.Their efforts made up for the lack of professional,and the specialization level of the Ministry’s officials had been greatly improved.