Abstract: Adjustable speed pumped storage power generation system (hereinafter referred to as "Adjustable speed unit") implements the adjustable input power under pumping conditions by adopts adjustable speed, so that the unit can dynamically adjust the power grid frequency both pumping and generating. Its high-speed response ability can quickly absorb the fluctuation of power system in a short time; and the unit can run with high efficiency under generating; it also can be used for such power stations with wide operation range of water head, which is more beneficial for hydraulic resources usage. With the new requirements of "carbon peaking and carbon neutrality" goal in China, the percentage of renewable energy with intermittent power generation which could be added to the power grid will be increased year by year 1. Adjustable speed units, as one of the powerful guarantee measures to maintain the safe and stable operation of the power grid, have been gradually recognized by the industry and paid more and more attention in recent years. Toshiba Corporation (hereinafter referred to as "Toshiba") has more than 120 years of experience in the field of hydro power generation. In terms of pumped storage units, Toshiba began to supply the equipment in 1965 and has a history of 57 years. In the 1990s, Toshiba took the lead in realizing the practicability of Adjustable speed pumping power generation system in the world 2. This paper mainly introduces and explains the technical features and performance of Toshiba adjustable speed pump storage unit, hoping to provide reference for the construction and development of adjustable speed pumped storage power station in China.