The design and implementation of a series of small-sized humanoid robots are proposed in this paper. The series includes three types of small-sized humanoid robots participating in AndroSot and HuroCup tournaments in FIRA 2010 and in RoboCup Japan Open 2011. Firstly, the architecture of the system hardware and software, the design process are addressed in details. Then, the new features of the robots and important principles for designing a robot are addressed in details. Finally, the three types of the robots are discussed and compared with the previous generations. This series of robots won the 3rd place in AndroSot tournament, the 1st place in HuroCup tournament in FIRA 2010, and the 2nd place in the KidSize Humanoid League in RoboCup Japan Open 2011.