The invention relates to the field of self-adaptive control, in particular to a method for improving absolute positioning precision based on a six-degree-of-freedom series mechanical arm. The method comprises the following steps of, firstly, acquiring tail end target spot information through a laser tracker, and preprocessing to carry out coordinate conversion between the mechanical arm and the laser tracker; then, establishing an exponential product model of the mechanical arm by applying Lie Groups and Lie Algebras, fusing the exponential product model with a method for solving a global minimum value through a sequential quadratic programming algorithm, and compensating tail end geometric errors generated by joint parameter deviation of the mechanical arm; and finally, solving an inverse kinematics solution through an actual point location obtained by the laser tracker and the exponential product model, carrying out model training by using a Gaussian process regression algorithm, carrying out compensation prediction on a non-geometric motion error, and inputting a predicted compensated angle value into a demonstrator. According to the method, the actual kinematics model parameters of the mechanical arm can be calculated more accurately, and the tail end point position error is reduced so as to improve the absolute positioning precision of the mechanical arm.