Abstract: Space inertial sensor is one of the key science payloads in space gravitational wave detection mission，aiming to detect infinitesimal change in gravitational wave.The research progress，detection principle and working mechanism of the inertial sensor were introduced and discussed to illustrate its technical challenges.The key technologies of the inertial sensor design were illustrated in three aspects：capacitance displacement sensing，electrostatic feedback control and ground evaluation.Then，the development and research status of inertial sensors worldwide were reviewed and summarized.It could be seen that the residual acceleration noise was the key indicator of the inertial sensor.It reached 3×10^-15m/(s²·Hz^1/2) orders of magnitude abroad.There are three orders of magnitude deficit between domestic and abroad.Thus，the study on high precision space inertial sensor has great strategic and scientific significance.To meet the needs of inertial sensors in China's future space gravitational wave detection missions，the research can focus on inertial sensor control system strategy，AC actuator parameter optimization，multi-degree-of-freedom decoupling control technology，and low noise technology.

Key words: space inertial sensor, space gravitational wave detection, capacitance displacement sensing, electrostatic feedback control, ground evaluation