Abstract: County governments played a very important role in the salt administration and the collection of salt taxes in the Qing dynasty. Local officials were responsible for selling salt and suppressing smuggling locally，while the central government designed strict tests on the salt law to ensure that the system works out. But counties had no independent administrative power in the institutional system of Qing dynasty，so they were often put into passive positions in the salt administration operation. The“conversion of the salt tax into a poll tax”in Dongguan County, Guangdong Province from the Kangxi to Qianlong Reign，was the result of mediating the conflicts between the superior policy from central government and the actual operation at the local level. This institutional change was the result of a process represented the local rejection of the orthodox salt law and the acquiescence of the central government for the reality of the daily operation of policies at the county level. This process has shown that in order to deal with the central government’s inspection of the administration of the salt law，county officers often took advantage of the change of political situations and flaws in the institutional system. Specifically, local officials sought to a balance between the central government and themselves，to achieve the purpose of changing local salt law, and ultimately ensuring the effective operations of the salt administration and the collection of salt tax in the Qing dynasty．