Based on the optimal estimation method, a satellite XCO retrieval algorithm was constructed by combining LBLRTM with VLIDORT. One-year GOSAT/TANSO observations over four TCCON stations were tested by our algorithm, and retrieval results were compared with GOSAT L2B products and ground-based FTS measurements. Meanwhile, the influence of CO line mixing effect on retrieval was estimated, and the research showed that neglecting CO line mixing effect could result in approximately 0.25% XCO underestimation. The accuracy of XCO retrievals was similar to GOSAT L2B products at cloud-free footprints with aerosol optical depth less than 0.3, and 1% accuracy of XCO retrievals can be reached based on the validation result with TCCON measurements.