An antenna detection system for detecting an antenna under test is provided. The antenna detection system includes a network analyzer and a test device. The test device includes: a first substrate; a second substrate parallel to the first substrate and carrying the antenna under test removably; and a standard antenna fixedly disposed on the first substrate to receive a test signal from a first port of the network analyzer and send a radiation signal according to the test signal. The antenna under test receives the radiation signal and sends a to-be-measured signal to a second port of the network analyzer. The network analyzer obtains a parameter according to the test signal and the to-be-measured signal and compares the parameter with a theoretical value calculated according to an operating frequency corresponding to the antenna under test and a constant interval to output a detection result of the antenna under test.