A thimble zirconia oxygen sensor was prepared with YSZ. The surfaces of the Pt electrode,electrolyte and their interface were observed with a scanning electron microscope (SEM).The sensor was examined with engine bench test to evaluate the essential performance. The basic function such as electromotive force output and response time was discussed. The oscillograph trace was also obtained and analyzed with four different frequencies. The experimental results reveal that the oxygen sensor has high performances meeting the demands of practical applications.