A device and method to perform on-line automatic flushing and cleaning for a steam turbine generator condenser, related with technology for flushing and cleaning of equipment during steam turbine generator operation, the apparatus includes: a polar coordinate traveling mechanical system, including one computer program polar coordinate control unit, which will control the servo motors to position the high-pressure water jet on the opening for Copper tube (or Titanium tube); the benefit for the invention is that, the polar coordinate traveling mechanical system move the high-pressure water jet to flush and clean each Copper tube (or Titanium tube) on condenser tube plate, to realize high-pressure water cleaning for each pipe during operation of generator, therefore, the heat exchanging efficient can be increased, further to reduce the consumption of coal for steam turbine generator, and archive the aim to saving coal, and reduction in generating cost.