Photovoltaic　(PV)　power　generation　has　become　viable　alternative　due　to　the　advantages　of　no　fuel　cost　and　abundance　of　sunlight.　In　a　grid-connected　PV　inverter　system,　besides　stability　and　reliability,　the　efficiency　is　always　an　important　factor.　To　generate　active　power　effectively,　the　gridside　current　must　be　in　phase　with　the　grid　voltage.　Further,　the　current　harmonics　must　be　low　enough　to　avoid　excessive　losses.　At　the　inverter　side,　the　efficiency　is　inverse　proportional　to　the　summation　of　switching　loss　and　conducting　loss.　Further,　for　the　switching　frequency　higher　than　several　Kilo-Hz,　the　dominant　loss　is　switching　loss.　This　means　that　to　have　high　efficient　gridconnected　PV　power　generation　system,　a　low　switching　loss　switching　strategy　for　inverter　to　produce　low　harmonics　currents　is　essential.　In　this　paper,　a　fixed　injection　PWM　is　proposed　to　achieve　both　low　current　harmonics　and　low　switching　losses.　The　proposed　method　can　be　directly　applied　to　the　three-phase　two-level　grid-connected　inverters　without　any　circuit　modification.　In　the　simulation,　a　30.8%　reduction　in　the　current　total　harmonics　distortion　is　obtained　comparing　with　the　conventional　switching　strategy.　Further　the　14.78%　improvement　of　inverter　efficiency　is　achieved.