In this paper, high thermal stability of Mn doped Y2/3Cu3Ti4O12 negative temperature coefficient (NTC) ceramics have been successfully fabricated by the combination of Pechini powder synthesis and solid-state reaction sintering. The substitution of Mn for Ti plays a critical role in controlling the phase structure, microstructure, electrical properties, and stability. The structure of as-sintered ceramics is a single Y(2/3)Cu(3)Ti(4)O(12)phase at x < 0.5, while the CuO phase begins to appear at x >= 0.7. X-ray photoelectron spectroscopy further confirms the change of cation concentration, one of the critical factors for electrical conductivity in Y2/3Cu3Ti4-xMnxO12 ceramics. In the temperature of -50-250 degrees C, the resistivity all decreases with increasing temperature and Mn content, the aging coefficient of all samples is within 0.4%, and the minimum can reach 0.2%. We strongly propose that the Mn substitution and Pechini method are highly desirable for the fabrication of high stability NTC thermistors for medi-temperature region application.