By　conducting　field　loading　tests　on　single　pile　and　composite　foundations　with　single　pile,　four　piles　and　nine　piles　with　different　lengths　and　area　replacement　ratios　about　compacted　soil-cement　pile　composite　foundation　in　unsaturated　clay　and　silt,　the　failure　pattern　and　the　effect　of　pile　length　and　area　replacement　ratio　on　bearing　capacity　of　composite　foundation　are　studied.　By　comparing　the　result　of　field　loading　test　in　different　flat　plates　with　sand　cushion,　the　existing　questions　in　evaluating　the　bearing　capacity　of　the　composite　foundation　are　analyzed　according　to　the　results　of　the　field　loading　tests　on　the　composite　foundation　with　compacted　cement-soil　single　pile.