This　paper　investigates　the　performance　of　advanced　super-resolution　restoration　algorithms　on　sonar　images.　Because　of　the　ability　of　being　able　to　shoot　images　in　relatively　dim　light　underwater,　sonar　has　been　more　and　more　widely　used　during　recent　years.　However,　images　taken　by　sonar　usually　have　low　resolution　due　to　the　positive　correlation　between　sonar　image　resolution　and　frequency　of　sonar　sensors,　as　well　as　the　negative　relationship　between　working　range　and　frequency　of　sonar　sensors.　For　more　accurate　observation,　resolution　of　sonar　image　should　be　increased.　Since　few　super-resolution　restoration　algorithm　has　been　designed　for　sonar　images,　we　selected　eight　existing　state-of-the-art　or　classical　super-resolution　restoration　algorithms　designed　for　optical　images.　Then　we　tested　their　performances　on　sonar　images　using　classical　and　state-of-the-art　image　quality　assessment　(IQA)　methods.　Finally　we　analyze　the　relationship　between　their　performances　and　the　content　of　sonar　images　by　comparing　the　visual　qualities　of　reconstructed　magnified　super-resolution　sonar　images.