The　bioavailability　of　trace　metals　in　sewage　irrigated　soils　ill　the　Southeastern　Suburbs　of　Beijing,　China　was　examined　by　using　in　vitro　digestive　fluid　extraction　method.　A　Sequential　chemical　extraction　(SCE)　procedure　was　used　to　measure　the　speciation　of　trace　metals　in　soil　samples,　including　Cd,　Pb,　Cu,　and　Zn.　The　average　concentrations　of　Cd.　Pb,　Cu,　and　Zn　were　2.23,　37.9,　59.9,　and　127.0　mg　kg(-1)　respectively,　indicating　the　heavy　pollution　of　soils　was　caused　by　Cd,　Cu,　Pb,　and　Zn　which　were　mainly　distributed　in　the　residual　phase,　whereas　Cd　was　mostly　in　the　carbonate　phase.　The　extraction　efficiencies　of　Cd,　Pb,　Cu,　and　Zn　quantified　by　the　in　vitro　digestive　fluid　extraction　method,　were　lower　than　those　by　the　SCE　procedure,　and　the　extraction　efficiencies　of　both　methods　followed　the　same　pattern:　Cd　＞Zn＞Pb＞Cu.　The　amount　of　trace　metals　extracted　by　using　these　two　methods　were　positively　correlated.　Therefore,　the　in　vitro　digestive　fluid　extraction　method　can　be　used　to　examine　the　bioavailability　of　soil-bound　trace　metals.