To study the thermal shrinkage properties of heat-shrinkable films, including shrinking force, contracting force and shrinking direction, and to determine the influences of the test temperature and the test duration to reach the maximum shrinking force on the shrinkage properties. According to the air heating principle test method in ISO 14616, the heat-shrinkable films were treated in the heated air to determine the shrinkage properties of various heat-shrinkable films at the optimal temperature (the temperature at which the maximum recorded shrinking force occurred between 15 s and 30 s). Multiple tests were conducted with three types of heat-shrinkable films with distinct thermal shrinkage properties at a series of temperature. The trends of maximum shrinking force and maximum contracting force of various heat-shrinkable films were different. And the shrinking direction was different for films with different materials and processing technologies. The same heat-shrinkable film demonstrated basically identical thermal shrinkage properties on different FST-02 film film thermal shrinkage testers. The test method and instrument specified in ISO 14616 were suitable for all kinds of heat shrinkable films, except that the sample direction and scope of preset temperature should be adjusted according to the material and the processing technique of the heat-shrinkable films.