Errors of parallel machine tool are major factors to restrict use of parallel machine tool in high precision which are unable to avoid. Total process of controlling and compensating errors of parallel machine tool began with decreasing the design errors, the design and manufacturing errors were firstly controlled, and then errors of parallel machine tool were compensated term by term or comprehensively in use of parallel machine tool. Process of compensating errors of parallel machine tool term by term was compensating temperature errors of a tool and hinge coordinates firstly, and then length errors of rods were compensated, and the errors were compensated term by term and in proper order in the cuter location dates of work piece. Process of compensating errors comprehensively was compensating errors of parallel machine tool comprehensively firstly, and then simulation processing and test processing were done respectively. Compensating errors has be stopped until the work piece meet the processing requirements.