For continuous assessment of the acid-base balance in the blood of hemodialysis patients and reducing mortality risk, this work proposes a chip for continuous monitoring of pH and PCO₂ in blood, utilizing electrochemical sensing and microfluidic technology. The chip combines pH and PCO₂ detection via a pH electrode and a carbonate ion-selective electrode, sharing a common reference electrode. The microfluidic test chamber ensures continuous blood flow and accurate detection by preventing air interference. The chip's pH detection performance was tested using Tris-HCl solutions ranging from pH 6.00 to 9.00, showing a detection sensitivity of 61.2 mV/pH with a standard deviation under 0.01 (n=10) for continuous detection of the same sample. The reproducibility test showed average relative errors of 0.46% (n=6), ensuring accurate detection of sample solutions within the pH 6.00-9.00 range. The sensor was tested in both blood gas control solutions and blood samples. In blood gas control solutions, the absolute errors for pH and PCO₂ detection were under 0.04 and 2.30 mmHg, with average relative errors of 0.23% and 1.94%, respectively. In blood samples, the absolute errors for pH and PCO₂ detection were under 0.05 and 3.50 mmHg, with average relative errors of 0.36% and 2.60%, respectively. Compared to commercial blood gas analyzers, the chip's small size allows it to connect to the hemodialysis pipeline, enabling continuous online detection of pH and PCO₂ in blood.