The invention discloses a method for reducing solid particle erosion to a supercritical steam turbine. The method comprises the following steps: 1) controlling the evaporation capacity, steam pressureand steam temperature of a boiler; 2) closing high and medium pressure main steam valves and regulating steam valves of the steam turbine, and opening a high pressure by-pass valve and a low pressureby-pass valve; 3) increasing the purge flow; 4) reducing the purge flow; 5) increasing the purge flow; 6) repeating the steps (1) and (5); and (7) collecting solid particulates. The method for reducing solid particle erosion to the supercritical steam turbine has the benefits as follows: by repeatedly changing the opening degree of the by-pass valves, the repeated changing of the purge steam pressure and flow is realized, the falling off of metallic oxides on the inner wall of the boiler tube is facilitated, the purging effect is ensured, the falling metallic oxides is blown into a condenserhot well through the steam turbine bypasses and collected and removed through a solid particle collecting device arranged in the hot well, solid particles generated are removed in time during the start-up phase of the turbine unit, the damage to the blade profile is avoided, the operation safety and economic efficiency of the turbine unit are improved, and the service life of the turbine unit is prolonged.