The invention discloses an asynchronous oscillation separation criterion based on a bus voltage frequency. According to the criterion, on the basis of the voltage frequency characteristics in the process of asynchronous oscillation, the changes of voltage frequency tracks on the two sides of the asynchronous center are opposite, the absolute value of the frequency difference of the two sides increases firstly and then decreases, and the maximum value exists; on the circumstance that the asynchronous center is transferred, the bus voltage frequency difference on the two sides of the asynchronous center passes zero, and inversion is generated. On the basis, the asynchronous oscillation center is judged by calculating the bus voltage frequency difference on the two sides of a branch, the bus voltage frequency difference increment and the bus voltage frequency increment, the criterion is easy to achieve, the criterion is suitable for transferring of the asynchronous center, the criterion is not limited by a power grid structure and an operation mode, and the asynchronous center can be positioned in half an asynchronous period.