The invention discloses a preparation method of an oxide reinforced platinum-rhodium-based composite wire. According to the method, platinum-rhodium alloy, metal Zr and rare earth Y are smelted into an alloy ingot by a high-frequency induction melting method, then the alloy ingot is prepared into a wire with the diameter of 0.01-1 mm by an extruding and drawing method, and then the alloy wire is conducted and heated by a direct-current or alternating-current power supply for internal oxidation; by controlling the magnitude of current, power-on time, atmosphere, power-on mode and the like, theinternal oxidation degree is controlled, and the distribution range and the size of oxide particles of different sections of materials in the composite material are realized, and therefore, the high-temperature mechanical property and resistivity of the composite material can be adjusted according to the use requirements. The invention further provides a platinum-rhodium-based composite wire withstaggered distribution of internal oxidation materials and alloy materials and a preparation method of the platinum-rhodium-based composite wire. The composite wire is excellent and stable in overallperformance, is suitable for industrial production, and can be used for long-service-life heating wires of instruments and apparatuses, thermocouples, electrode materials, high-temperature structure materials and the like.