With the rapid development of new energy, such as photovoltaic and wind power, the installed capacity of new energy generation which has been an important part of power energy is increasing. As a vital part of gateway electric energy metering device, secondary load has a non-ignorable influence on error of transformer. This paper makes a comprehensive statistics of the secondary load of metering transformers in new energy generation gateways of Henan power grid. Results show that most of the secondary loads of metering transformers are too large, which is not only unable to meet the requirements of the regulation, but also makes a negative effect on the metering error. Practical experiment shows that unreasonable selection of secondary load leads to deviation of metering error, even exceeding to the error limit. Finally, it puts forward the selection proposals for the secondary load of metering transformer in new energy generation gateways, which provides reference for technicians engaged in electrical energy measurement. This work is supported by Fundamental Research Funds for the Central Universities (No. 2018QN072) and Science and Technology Project of State Grid Henan Electric Power Company (No. 52170217001C).