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This invention provides a P-type passivated contact structure and its preparation method. The P-type passivated contact structure includes a silicon substrate, a first silicon oxide layer, a first polycrystalline silicon layer, a second polycrystalline silicon layer, and a hydrogen-containing dielectric layer. The silicon substrate has a diffusion region near the surface of the first silicon oxide layer. The surface of the first silicon oxide layer near the first polycrystalline silicon layer has a native pinhole defect structure generated by plasma bombardment. The first polycrystalline silicon layer is made of carbon-doped boron-containing polycrystalline silicon, wherein the boron and carbon doping concentrations gradually increase away from the first silicon oxide layer, and the thickness is greater than or equal to 8 nm. The second polycrystalline silicon layer is also made of carbon-doped boron-containing polycrystalline silicon, with a thickness greater than 10 nm. The interfacial silicon oxide surface of this invention has a high density of pinhole defects, and using carbon-doped boron-containing amorphous silicon as the source layer can reduce oxide layer defects caused by interfacial boron enrichment, achieving excellent surface passivation and selective carrier collection, and reducing surface recombination current density.