Here are proposed methods to evaluate the accuracy of measuring heads (MH) of coordinate measuring machines (CMM). Kinematic touch-trigger, piezoresonant touch-trigger and scanning 3D probes are investigated as the most often being used for the 3D measurements. The dominating errors of kinematic touch-trigger probes are expressed by the polygonal (triangular) characteristics of their kinematics and by random dispersion of the contact forces. These features characterize the piezoresonant touch-trigger probes as well but instability of resonance of the system components are also presented here. Dominating error’s characteristics of the scanning probes consist of the instability of pushing the probe stylus out of the measured surface by dynamical forces. Some mathematical models, space error’s approximation and results of experimental investigation of the measuring heads are presented. It may be used for the improvement of CMM and other measuring equipment.