Abstract: With the increasing penetration of new energy, the inertia response and primary frequency modulation capability of high proportion new energy power system have undergone profound changes. Considering the influence of new energy replacement synchronizer on the system frequency characteristics, the functional positioning and cooperation relationship between inertia response and primary frequency modulation in new power system has become a prominent research topic. In this paper, the power response and energy conversion mechanism of inertia response stage and primary frequency modulation stage in the process of frequency disturbance are initially explained. Secondly, the frequency response model of the system is established in MATLAB/Simulink, and the matching relationship and minimum requirements of the system inertia level and primary frequency modulation speed are investigated under the constraint of not causing low frequency load reduction. Additionally, the limit new energy permeability of the system is further analyzed when the new energy does not provide inertia and primary frequency modulation. Finally, the premise that new energy can provide inertia and frequency modulation support is established, the frequency modulation requirements for new energy units are proposed from three aspects of inertia support level, primary frequency modulation margin and primary frequency modulation speed, and the system's frequency modulation requirements for new energy are compared under the penetration levels of 50%, 75% and 100%. It provides reference for determining the primary frequency modulation speed of new energy units in a high-proportion new energy power system.