Abstract: The gravitational reference sensor(also known as the inertial sensor)is a key load in the task of space gravitational wave detection.After the test mass is experienced in various cosmic environments,due to the action of some high-energy particles,the charge will gradually accumulate in the test mass.When the accumulation of charge growth over time to a certain extent,the resulting noise will affects drag-free control of the spacecraft and the achievement of related mission scientific objectives.The charge accumulation mechanism of test mass is analyzed.Several structures of charge control for test mass by photoelectric effect are introduced.The experiments are designed to explore the charge control of test mass by 250 nm ultraviolet light.Finally,the control methods of test mass charge are summarized.