High-speed railways are designed with high speed and deformation control requirements. Due to the structural mechanical characteristics and the material properties of concrete, the concrete arch bridge inevitably exhibit downward deflection in operation, which directly affects the track alignment and traffic safety. In order to ensure the driving safety and comfort of Beipanjiang Bridge in Shanghai Kunming passenger dedicated line, an automatic deformation observation system was established to analyze the deformation and temperature changes. The extraction methods of creep and temperature effect were studied. The impact factor of temperature and deformation are determined with polynomial fitting. The results show that: (1) the accuracy and effectiveness of the observation system satisfy the requirements; (2) the bridge deck alignment is sensitive to the temperature change. The uneven settlement is large under at low temperature, which decreases as the temperature rises; (3) using the proposed creep analysis method, the relative creep deformation is only about 6% different from that of the theoretical value, which meets the computational precision requirements in practical engineering.