Herein,　a　competitive　luminol　chemiluminescence　immunosensor　based　on　a　microfluidic　chip　was　developed　to　detect　ractopamine　(RCT)　both　in　phosphate　buffer　and　swine　urine　samples.　The　immunosensor　can　provide　a　liner　range　of　0.5-40　ng/mL　and　a　high　sensitivity　with　a　limit　of　detection　of　0.97　ng/mL　for　RCT　detection　in　swine　urine.　Good　rates　of　recovery　in　negative　swine　urine　samples　were　achieved　over　the　RCT　concentration　ranging　from　0.5　to　40　ng/mL.　The　proposed　method　offered　a　promising　analytical　scheme　for　the　on-site　determination　of　RCT.