HVDC transmission technology plays an irreplaceable role in long-distance large-capacity power transmission and AC grid interconnection, and its stable and healthy operation is of great significance to the power grid. The converter valve is the core equipment of DC transmission project, and the saturation reactor is an important protection element in the converter valve, whose reliability is directly related to the long-term safe and stable operation of DC transmission system. Due to the high-frequency impulse stresses of electricity, heat and vibration, the saturation reactor is prone to parameter drift, which threatens the operation safety of DC projects. This paper proposes saturation reactor field testing and performance evaluation method and develops field testing device as well as dedicated software. With the field testing device, the detection of key electrical parameters of saturation reactors in operation can be effectively realized, thus ensuring the safe and reliable operation of high-voltage DC converter valve.