A device and a method for determining a microvibration effect on a millisecond-level space optical sensor are provided. The device includes: a light source, a star simulator, an air flotation vibration isolation platform, a suspension system/air flotation system, a zero stiffness system, a supporting system, a six-degree-of-freedom microvibration simulator, a signal driving apparatus, and a data acquisition and processing system. In the device for determining a microvibration effect on a space pointing measurement apparatus, a free boundary condition and a zero gravity environment are simulated by using a suspension system and a zero stiffness system. A light source and a star simulator simulate a star at infinity. A six-degree-of-freedom microvibration simulator simulates an on-orbit microvibration mechanical environment which is used as an input of a test. Extremely high-precision sensors collect system response data.