The properties and protein structural features of dry noodles added with soybean protein isolate (SPI) were analyzed by texture analysis,NMR and FT-IR technologies. The results showed that SPI had significant influence on texture and cooking properties of dry noodles. T21 of dry noodle added with SPI was increased while T22 was decreased. When addition level of SPI was increased, hydrosulphonyl content of dry noodle fluctuated increased (10.53~14.22 μmol/L) and disulfide bond content decreased in volatility (12.26~6.56 μmol/L). Meanwhile, the characteristic peaks in the secondary structures of protein, including anti-parallel β-sheet, aggregated strands, β-strand, α-helix, β-sheet, extension and intramolecular coupling were appeared. With SPI content increased, the percentage of protein secondary structures displayed significant difference. The bending distance to dry noodle and percentage of characteristic peak in protein secondary structures of anti-parallel β-sheet, aggregated strands, and β-strand were highly significant positive correlation. The percentage of characteristic peak in protein secondary structure including α-helix, β-sheet, reverse parallel structure was negative correlation.