The　phenomenon　of　efficiency　droop　is　comprehensively　investigated　in　an　asymmetric　GaN-based　laser　diode　(LD).　Numerical　simulations　and　experiments　are　both　conducted.　It　is　found　that　with　the　introduction　of　a　sandwiched　GaN/InAlN/GaN　lower　quantum　barrier　(LOB)　instead　of　the　bulk　GaN　LQB　in　an　asymmetric　GaN-based　high-power　blue　LD,　the　efficiency　droop　is　effectively　mitigated　to　only　9.7%　under　continuous-wave　operation　with　no　degradation　in　the　crystal　quality.　Compared　with　the　conventional　asymmetric　GaN-based　LD,　the　wall-plug　efficiency　is　successfully　increased　by　24.7%　from　15.8%　to　19.7%　at　high　injection　current　of　2000　mA,　promoting　the　increase　of　slope　efficiency　and　output　power,　while　the　threshold　current　is　reduced　by　15.2%.　These　improvements　are　primarily　attributed　to　the　inserted　high-quality　InAlN　thin　barrier　layer,　which　could　form　an　extra　potential　barrier　beneath　the　first　InGaN　quantum　well　to　remarkably　alleviate　the　hole　overflow　from　the　active　region　and　enhance　the　radiative　recombination　rate.