The terminal device can generate a monophonic signal of a specified frequency, and can transmit the monophonic signal by using a specified receive antenna or transmit antenna of the terminal device. The terminal device has a function of transmitting the monophonic signal of the designated frequency by using any specified antenna. Therefore, a measurement system for an antenna complex number pattern of the terminal device can accurately measure a complex number pattern of each antenna of the terminal device in a manner in which the terminal device transmits the monophonic signal of the specified frequency by using each receive antenna or transmit antenna. The measurement system can further obtain an accurate measurement result when a MIMO OTA performance test is performed on the terminal device according to the complex number patterns of all the antennas of the terminal device.