A system for audio and video synchronization test, applied to a performance test of an audio and video transmission and playing device to be tested, wherein the system comprises: a video signal generating apparatus, disposed in the vicinity of the device to be tested, configured for generating an image test signal; the device to be tested collects and transmits the image test signal to a first output end of the device to be tested, so as to output an image transmission test signal; a video delay test apparatus, collecting the transmission image test signal output by the device to be tested and a real-time image test signal generated by the video signal generating apparatus currently and comparing the same, so as to obtain a video delay time of the device to be tested; an audio signal generating apparatus, disposed in the vicinity of the device to be tested, configured for generating a sound test signal; the device to be tested collects and transmits the sound test signal to a second output end of the device to be tested, so as to output a transmission sound test signal; an audio delay test apparatus, collecting the transmission sound test signal output by the device to be tested and a real-time sound test signal generated by the audio signal generating apparatus currently and comparing the same, so as to obtain an audio delay time of the device to be tested; and a processing apparatus, connected to the video delay test apparatus and the audio delay test apparatus, respectively, so as to obtain a time difference between the video delay time and the audio delay time; characterized in that the video signal generating apparatus comprises a LED image generator, the LED image generator comprises at least a line of N LED lights arranged along a straight line; and each of the N LED lights is illuminated in sequence at a frequency of f in the same direction along which the LED lights extend, and illumination time for each of the LED lights is 1/ (N ∗ f), and the video delay time is: T 3 = n ƒ + n − 1 * 1 N * ƒ, n ≥ 1 T 3 =0, n=0; wherein, T 3 is the video delay time, N is a positive integer greater than or equal to 5, n is a sequence number difference between the sequence of the LED light illuminated by a pulse image of the real-time image test signal and the sequence of the LED light illuminated by the pulse image of the transmission image test signal, and n is a natural number, and an error range of T 3 is 0 − 2 * 1 N ∗ ƒ. a video signal generating apparatus, disposed in the vicinity of the device to be tested, configured for generating an image test signal; the device to be tested collects and transmits the image test signal to a first output end of the device to be tested, so as to output an image transmission test signal; a video delay test apparatus, collecting the transmission image test signal output by the device to be tested and a real-time image test signal generated by the video signal generating apparatus currently and comparing the same, so as to obtain a video delay time of the device to be tested; an audio signal generating apparatus, disposed in the vicinity of the device to be tested, configured for generating a sound test signal; the device to be tested collects and transmits the sound test signal to a second output end of the device to be tested, so as to output a transmission sound test signal; an audio delay test apparatus, collecting the transmission sound test signal output by the device to be tested and a real-time sound test signal generated by the audio signal generating apparatus currently and comparing the same, so as to obtain an audio delay time of the device to be tested; and a processing apparatus, connected to the video delay test apparatus and the audio delay test apparatus, respectively, so as to obtain a time difference between the video delay time and the audio delay time; characterized in that the video signal generating apparatus comprises a LED image generator, the LED image generator comprises at least a line of N LED lights arranged along a straight line; and each of the N LED lights is illuminated in sequence at a frequency of f in the same direction along which the LED lights extend, and illumination time for each of the LED lights is 1/ (N ∗ f), and the video delay time is: T 3 = n ƒ + n − 1 * 1 N * ƒ, n ≥ 1 T 3 =0, n=0; wherein, T 3 is the video delay time, N is a positive integer greater than or equal to 5, n is a sequence number difference between the sequence of the LED light illuminated by a pulse image of the real-time image test signal and the sequence of the LED light illuminated by the pulse image of the transmission image test signal, and n is a natural number, and an error range of T 3 is 0 − 2 * 1 N ∗ ƒ.