SnO2 hollow nanofibers with different amount of La-doped were prepared by electrostatic spinning method. Their composition, morphology and structure were characterized by XRD, SEM, BET and XPS respectively and their gas sensing properties were also investigated. The results showed that the hollow nanofibers with the molar ratio of tin to La of 7% had the best sensitivity to ammonia of 500 ppm at the temperature of 300 degrees C, and the sensitivity value reached 480, which was 10 times that of pure SnO2. And its response time was also significantly shortened.