Through　theoretical　discussion　of　the　cross-hole　ultrasonic　testing　method　and　combining　the　engineering　case,　the　quality　of　pile　body　concrete　and　the　possible　positions　of　pile　defects　are　detected　by　ultrasonic　curve;　and　used　the　PSD　criteria　as　aided　analysis,　the　nature　and　range　of　pile　defects　are　estimated.　Practice　shows　that　the　cross-hole　ultrasonic　method　for　quality　inspection　of　cast-in-place　concrete　pile　can　give　visual　and　reliable　results.　Thus,　it　is　an　effective　inspection　method　for　the　quality　of　pile　body　concrete.