A　new　type　of　continuous　harvester　is　designed　to　address　the　problems　of　high　labor　cost　and　low　efficiency　in　the　process　of　harvesting　lettuce　in　greenhouse　hydroponics.　The　designed　harvester　is　mainly　composed　of　three　parts,　namely,　reciprocating　cutter,　driving　mechanism,　and　belt　conveyor.　The　response　surface　method　is　used　to　establish　the　mathematical　model　between　the　force　acting　on　the　lettuce　roots　and　the　reciprocating　speed　of　the　cutter,　the　inclination　angle　of　the　cutter,　and　the　conveying　speed　of　lettuce.　The　reliability　of　the　mathematical　model　is　verified,　and　the　optimal　parameter　combination　of　the　force　on　the　lettuce　root　is　obtained.　Considering　the　actual　harvesting　method,　the　destruction　rate,　damage　rate,　and　success　rate　of　lettuce　are　used　as　the　design　indexes　in　the　experiment.　Results　showed　that　the　force　on　the　lettuce　stem　is　the　smallest　under　the　optimal　parameter　combination　of　the　reciprocating　motion　speed　of　the　cutting　blade　(100　mm/s),　the　inclination　angle　of　the　cutting　blade　(2.31　degrees),　and　the　conveying　speed　of　the　lettuce　(64.49　mm/s).　When　the　minimum　force　is　1.91　N,　the　destruction　rate　of　lettuce　harvest　is　1.85%,　the　damage　rate　of　lettuce　is　3.71%,　and　the　success　rate　of　lettuce　harvest　is　94.44%.　This　study　offers　a　potential　solution　for　the　automatic　harvesting　of　hydroponic　lettuce　in　a　greenhouse.