Parasitic　oscillation　in　the　slab　amplifier　affects　the　efficiency　of　laser　amplifier　and　reduces　the　stored　energy　of　slab　crystal.　The　surface　of　Nd:YVO4,　gain　of　grazing　incident　slab　amplifier　was　processed　to　suppress　the　parasitic　oscillation　in　the　slab　and　improve　the　energy　storage　ability　of　slab　crystal.　Through　ion　sputtering　method,　the　germanium　was　plated　on　top　and　bottom　surface　and　the　back　surface　to　suppress　the　parasitic　oscillation.　In　germanium　plated　and　without　germanium　plated　conditions,　the　slab　oscillator＇s　output　characteristics　were　compared　between　free　oscillation　and　Q-　switched　mode,　threshold　current　reduced　15%　in　plating　germanium　slab　oscillator,　and　the　stored　energy　improved　86.9%.　The　beam　quality,　pulse　duration　and　spot　pattern　of　plating　germanium　slab　oscillator　were　basically　the　same　to　without　plating　germanium　slab　oscillator　in　Q-switched　mode.　Experimental　result　indicates　plating　germanium　on　the　face　of　slab　is　an　effective　method　to　suppress　the　parasitic　oscillation　and　improve　the　energy　storage　ability　of　crystal.　©　2017,　Editorial　Board　of　Journal　of　Infrared　and　Laser　Engineering.　All　right　reserved.