Abstract: Inertia plays a key role in the resistance of power system to disturbances. With the increase of renewable energy penetration, the characteristics of low inertia and uneven spatial and temporal distribution of inertia in the power system are becoming more and more prominent, and it is of great significance to accurately evaluate the node inertia distribution in the power grid. To this end, this paper proposes an evaluation method for node inertia distribution based on small disturbance frequency measurement data. First, the mathematical coupling mechanism between frequency and inertia is analyzed, and the inertia distribution characteristics of the new power system are revealed. Then, based on the frequency measurement data and system power supply parameters under a single small disturbance, a node equivalent inertia definition method considering the horizontal deviation of each node frequency compared to the change of the center frequency of the system, and a calculation method for the rate of change of the frequency of each node based on adaptive-order polynomial fitting are proposed, respectively. The node equivalent inertia can be calculated by combining the two methods under a single small disturbance. Further, in view of the fact that the node equivalent inertia calculated under a single small disturbance has a certain random error, a dynamic aggregation strategy that takes into account the evaluation results of multiple disturbance events is proposed, and an evaluation method for node equivalent inertia distribution applicable to the new power system is formed. Finally, the effectiveness of the proposed method is verified by taking the IEEE 39-bus system and a certain provincial power grid in China as cases. The results show that the proposed method requires a small amount of data, and only the frequency measurement data collected by the synchrophasor measurement unit at each node is needed to realize the effective evaluation of grid inertia distribution, and the evaluation results have high accuracy and strong timeliness.