With the increase in the proportion of new energy sources such as photovoltaic and wind power accessing the power grid, the non-power frequency electrical quantities in the grid have increased, which has an impact on traditional electric energy metering equipment. The existing space electric field measuring instrument is vulnerable to interference from non-measured phases, and the actual operation of the improved capacitive voltage transformer (CVT) is complex. This paper analyzes the structure of the standard capacitive voltage divider and the influence of the load on it, proposes to improve its performance by increasing the secondary load impedance, and designs an isolation amplifier. The experimental results show that the isolation amplifier has good frequency characteristics and power frequency high voltage performance, and can effectively improve the loading capacity of the capacitive voltage divider.