The invention relates to a precision calibration method and device for distributed POS. The method includes: firstly calibrating the relative pose relation of a first camera and a second camera without a common field of view; letting the first camera and the second camera shoot a first sub-node target and a second sub-node target respectively, and measuring the poses of the first sub-node and thesecond sub-node in a camera coordinate system respectively; unifying the pose data of the first camera and the second camera into one measurement reference coordinate system, and calculating the baseline length and baseline angle between the first sub-node and the second sub-node; and calibrating the precision of the baseline length and baseline angle data measured by distributed POS. The method and device provided by the invention have the advantages of high precision and strong anti-interference ability, and can be used for pose precision calibration of existing low precision and high precision distributed integrated navigation systems.