A　compact,　lower　cost,　angular　multiplexing　multi-pass　slab　amplifier　is　reported.　The　traditional　rod　structure　has　serious　optical　distortion,　including　thermal　focusing,　double　focusing　caused　by　stress,　stress　birefringence.　The　slab　structure　can　reduce　the　impact　of　these　effects,　and　improve　the　quality　of　laser　beam.　The　slab　laser　geometry　permits　efficient　use　of　the　unsaturated　gain　medium　by　using　angular　multiplexing.　Standard　methods,　such　as　polarization　multiplexing,　require　the　beam　to　be　near　to　retrace　its　path.　This　retracing　can　result　in　feedback　into　the　oscillator　source　and　will,　lead　to　parasitic　oscillation　of　the　amplifier.　These　problems　due　to　retracing　its　path　can　be　reduced　if　using　angular　multiplexing.　A　passively　Q　switched　laser　with　repetition　frequency　of　20　kHz,　pulse　duration　of　2.5　ns　and　average　output　power　of　0.5　W　is　used　as　the　master　oscillator.　Comparing　the　two　ways　of　three-pass　amplifications,　we　realize　a　method　to　effectively　amplify　the　seed　laser　with　nanosecond　pulse　duration　and　microjoule　energy.　When　the　seed　laser　is　totally　reflected　in　the　Nd:YVO4　slab,　the　average　output　power　of　3.2　W　is　achieved.　Compared　with　other　methods,　this　method　can　obviously　eliminate　the　thermal　lensing　effect　and　enhance　the　output　power.