It　is　necessary　to　assess　network　video　quality　in　real-time　that　depends　on　network　transmission　statement　to　subjective　visual　without　any　referenced　video　sequences.　Focusing　on　distortion　of　videos　caused　by　network　packet　loss,　it　is　found　that　network　packet　loss　in　different　frames　with　different　decoding　types　causes　different　sustained　effects　of　video　distortion,　and　it　exists　significant　association　between　visual　feelings　caused　by　network　packet　loss　and　movement　activity　of　lost　video　content.　Hence,　a　no-reference　assessment　model　for　video　quality　is　proposed　based　on　movement　activity.　This　model　analyzes　the　damage　caused　by　the　packet　loss　of　the　code　stream　received　by　client,　and　marks　the　damaged　macro　block　to　associate　the　damaged　macro　blocks＇　distortion　continuing　effect　and　movement　activity　with　videos＇　quality.　Then,　it　completes　the　quality　assessment　of　videos　without　reference　of　any　original　video　sequence　or　video　decoding.　Experimental　results　show　that　this　method　has　a　small　amount　of　calculation,　a　high　real-time　and　a　high　degree　of　consistency　with　the　subjective　assessment　results.