This research mainly combines electronic components and fabrics, uses electrodes to collect signals to analyze the subjects' sodium concentration and sweat flow, and develops highly hydrophilic thin films of Polyacrylic acid / Cellulose nanocrystals (PAA / CNC) sensor. Prepare PAA/CNC light-curing hydrogels with different concentration ratios, conduct contact angle, FTIR spectrum, swelling ratio (Swelling Ratio), SEM, and EIS wetted area analysis and comparison, and select the PAA/10 CNC concentration ratio as Best Sweat Sensing Electrodes. The result of strengthening the adhesion between CNC and PET sheets can effectively improve the hydrophilicity of the film, reduce the difference in hydrophilicity and hydrophobicity between the electrode and the fabric, and enhance the electrode sensing sensitivity. The capacitance value results showed an approximately fivefold increase compared to the control group 5~10 times the sensitivity. This research develops a sensitive and stable film for real-time monitoring of sweat, and combines it with Bluetooth for application in smart clothing devices.