City is being the major body to response to the climate changes and developing the low-carbon economy. Transition to low carbon city has become the world trend for urban development in future. It is relative frontier concept to develop the low-carbon city. With the scattered and tentative features of current low-carbon practice，there has not yet formed a systematic low-carbon economic development framework in China’s cities. There are some misunderstandings on low-carbon economy in some cities，under-estimating the difficulty of building low-carbon cities. The intent of applying to become the pilot cities aims to gain national policy support. Meanwhile，some commercial ratings behaviors are not conducive to creating a low-carbon city construction environment. In order to encourage and guide the boom of low-carbon urban construction，it is urgent to promulgate appropriate national guidance on low-carbon city construction and establish corresponding comprehensive evaluation index system.