Abstract: With the rapid development of wind farms and photovoltaic plants, the future power systems might experience the decline of fundamental frequency characteristics due to the severe reduction of power supply of thermal and hydropower plants. In order to study such decline, the frequency model of the power system highly penetrated by new energy was proposed along with its transfer functions. And the steady state errors（SSEs） of frequency due to frequency or power step response were deployed in this paper. A thorough analysis was performed on the stability and the SSEs of the highly penetrated power system. The dynamic frequency response characteristic（DFRC） of the highly penetrated power system was defined and the upper limit of the proportion of new energy generation was estimated. Assuming that the capacity of frequency control provided by the new energy generation was enough, the two schemes of frequency control of new energy generation were introduced and compared, which make the difference in the SSEs of the highly penetrated power system. Finally, time domain digital simulations were performed to verify the proposed conclusions and to reveal the trend of frequency characteristics of future power systems.