Embodiments of the present disclosure provide a method, a device and a system for evaluating a user experience value of video quality. The method is: acquiring an uplink packet of a user equipment for requesting to watch an OTT video, where the uplink packet is transmitted by the user equipment to a video server storing the OTT video and carries request information of the user equipment on the OTT video; acquiring a downlink packet corresponding to the uplink packet, where the downlink packet is transmitted by the video server to the user equipment and carries the OTT video, and the OTT video is transmitted by the video server according to the request information in the uplink packet; buffering the downlink packet; and in response to determining that the buffered downlink packet satisfies a resolving condition, resolving the OTT video in the buffered downlink packet to generate a user experience value.