This investigation intends to establish an experimental test platform for a small vertical-axis wind turbine (VAWT), which is installed on the rooftop of a building. The experiment platform designed here is flexible and suitable for executing the systematic performance evaluation on different types of VAWT. By utilizing the data acquisition system (DAQ), all environmental information and power data from sensors and generator on the platform are recorded and transferred to the computer automatically. Later, these analogy signals are transformed to digital format for transmitting into computer. Also, with the aids of a visual software programming within the framework of Labview, the real-time monitoring on the input/output parameters of generator and the wind condition on the rooftop can be accomplished simultaneously. Afterwards, the data processing and in-depth analysis on the experimental outcomes are carried out via the established computer program. Consequently, the on-site performance of the wind turbine generator system is attained in an automatic and systematic manner. Moreover, to ensure for providing sufficient data and its accuracy, statistic concept is enforced to judge whether the test data are qualified or not in the data-processing procedure. Regarding the safety evaluation on this test platform, the numerical models of the wind turbine and platform are analyzed numerically via ANSYS Workbench to obtain the force exerting on the main shaft and blades. This force distribution can be analyzed for checking if they can stand and meet the safety criterion under various wind speeds. In summary, together with the data-acquisition software programmed under the framework of Labview, this experimental system can provide the capability for monitoring, recording, and filtering these test data in an rigor manner, and is appropriate for executing the R&D and performance evaluation on different VAWTs.