The present invention discloses a method, an apparatus, and a system for monitoring quality of an OTT video, which can implement monitoring of quality of an OTT video in a convenient manner. An OTT video monitoring apparatus intercepts a message sent by an OTT video terminal to an OTT video source for requesting to watch an OTT video; sends a response message to the OTT video terminal, where the response message carries a monitoring instruction, so that the OTT video terminal obtains identifier information of the OTT video according to the monitoring instruction; the OTT video monitoring apparatus obtains the identifier information of the OTT video from the OTT video terminal; and monitors quality of the OTT video according to the identifier information of the OTT video.