The utility model discloses an online oil filter of steam turbine lubricating oil system device and steam turbine lubricating oil system, wherein, the online oil filter of a steam turbine lubricating oil system device, include back that oil branch pipe, colating oil branch pipe and essence strain oil branch pipe, it strains oil branch pipe and all assembles the union coupling with the oil return to return oil branch pipe, colating oil branch pipe and essence, colating oil branch pipe with the essence strain oil branch pipe respectively with oil branch pipe parallel connection returns, installation colating oil filter core among the colating oil branch pipe, colating oil filter core carries out the coarse filtration to lubricating oil, the smart oil strain filter core of installation among the oil branch pipe is strained to the essence, smart oil strain filter core carries out the essence to lubricating oil and filters, return and to install first governing valve on the oil branch pipe, install the second governing valve on the colating oil branch pipe, the essence is strained and is installed the third governing valve on the oil branch pipe. The utility model discloses simple structure, one -time Setup uses all the life, has simplified the oil strain process, has satisfied real -time online oil filter.