Abstract: High-voltage, large-capacity and broadband admittance measurement equipment is an important equipment to solve the problem of admittance modeling under the control of black/gray box of renewable energy grid-connected power generation device such as wind and solar. Firstly, a broadband admittance measurement topology based on cascaded multilevel structure and its broadband linear output control method is adopted in this paper. A 35kV/1MVA broadband admittance measurement equipment is developed, which can measure admittance of renewable energy grid-connected power generation device on the high-voltage side, and the measurement bandwidth is 10Hz~1kHz. A smooth switching control method for broadband admittance measurement equipment is proposed. The admittance measurement can be guaranteed by controlling the switching sequence of various switches and the start-stop sequence of admittance measurement equipment and renewable energy grid-connected power generation device. The measuring equipment will not have an impact on the equipment itself and the measured object during the switching process, especially to avoid the negative effects caused by the inrush current of the transformer. Then, in order to solve the problem that the measured phase of the non-diagonal elements in the admittance matrix is confused in the traditional frequency-coupling admittance measurement method, a frequency-coupling admittance measurement method based on the phase correction of the fundamental voltage of the grid is proposed, which can accurately measure the admittance characteristics of renewable energy grid-connected power generation device. Finally, simulation and field experiments prove the effectiveness of the proposed 35kV/1MVA broadband admittance measurement equipment design scheme and frequency-coupling admittance measurement method.