The　development　of　degradable　plastic　foams　is　in　line　with　the　current　development　concept　of　being　pollution　free　and　sustainable.　Poly(lactic　acid)　(PLA)　microporous　foam　with　biodegradability,　good　heat　resistance,　biocompatibility,　and　mechanical　properties　can　be　successfully　applied　in　cushioning　packaging,　heat　insulation,　noise　reduction,　filtration　and　adsorption,　tissue　engineering,　and　other　fields.　This　paper　summarizes　and　critically　evaluates　the　latest　research　on　preparing　PLA　microporous　materials　by　supercritical　carbon　dioxide　(scCO2)　physical　foaming　since　2020.　This　paper　first　introduces　the　scCO2　foaming　technologies　for　PLA　and　its　composite　foams,　discusses　the　CO2-assisted　foaming　processes,　and　analyzes　the　effects　of　process　parameters　on　PLA　foaming.　After　that,　the　paper　reviews　the　effects　of　modification　methods　such　as　chemical　modification,　filler　filling,　and　mixing　on　the　rheological　and　crystallization　behaviors　of　PLA　and　provides　an　in-depth　analysis　of　the　mechanism　of　PLA　foaming　behavior　to　provide　theoretical　guidance　for　future　research　on　PLA　foaming.　Lastly,　the　development　and　applications　of　PLA　microporous　materials　based　on　scCO2　foaming　technologies　are　prospected.　©　2022　by　the　authors.