The invention discloses a dynamic real-time compensation system for positioning errors of a numerical-control machine tool. The system comprises an error compensation hardware system and a compensation software platform based on network data interaction. The hardware system serves as a carrier and an executing part of compensation software and is used for achieving connection, communication, data storage and human-computer interaction between all functional modules. A programming mode oriented to objects is adopted for the software system, the software system has data interaction with CNC through an Ethernet, and therefore temperature signals can be collected and preprocessed, a positioning error mathematical model can be automatically established, and real-time calculation of the positioning errors, the intelligent model adjusting function, and training and optimizing on a self-learning model can be achieved. Due to cooperative work of the software system and the hardware system, the dynamic real-time compensation for the positioning errors of the numerical-control machine tool is achieved. The compensation system for the positioning errors is easy to operate, wide in application range and capable of meeting positioning error compensation requirements of various numerical-control machine tools and has great practical and commercialized application significance in improving machining accuracy of the numerical-control machine tools.