We　propose　a　fiber-solid　hybrid　system　which　consists　of　a　semiconductor　saturable　absorber　mirror　(SESAM)　mode-locked　fiber　seed　with　a　pulse　width　of　10.2　ps　and　a　repetition　rate　of　18.9　MHz,　a　two-level　fiber　pre-amplifier　and　a　double-passing　end-pumped　Nd:YVO4　amplifier.　In　the　solid-state　amplifier,　to　enhance　the　gain　and　the　extraction　efficiency,　a　specially　designed　structure　in　which　the　seed　light　passes　through　the　gain　medium　four　times　and　makes　full　use　of　population　inversion　is　used　as　the　double-passing　amplifier.　Besides,　the　beam　filling　factor　(the　ratio　of　the　seed　light　diameter　to　the　pump　light　diameter)　and　the　thermal　lens　effect　of　the　double-passing　amplifier　are　considered　and　its　optical-to-optical　conversion　efficiency　is　further　improved.　To　preserve　the　beam　quality　of　the　double-passing　amplifier,　a　new　method　of　spherical-aberration　self-compensation　based　on　the　principles　of　geometrical　optics　is　used　and　discussed.　Our　system　achieves　a　maximum　average　power　of　9.5　W　at　the　pump　power　of　28　W,　corresponding　to　an　optical-to-optical　efficiency　of　27%　.　And　the　beam　quality　factor　M2　reaches　1.3　at　the　maximum　output　power.