The　paper　aims　to　develop　a　rapid,　simple　and　single　copy　gold　immunochromatographic　strip　assay　method　for　the　quantitative　determination　of　trace　concentrations　in　serum　or　urine.　The　image　of　gold　immunochromatographic　strip　is　taken　by　CCD,　and　after　a　proper　process,　the　reflective　integral　optical　density　is　extracted　as　the　feature　based　on　Lambert-beer　law.　In　order　to　improve　the　measure　property,　the　relative　detection　method　is　applied　by　which　the　interference　in　the　test　and　control　lines　can　be　cancelled　out　each　other.　The　proposed　method　is　tested　by　the　quantitative　detection　of　human　chorionic　gonadotropin　(hCG)　using　14　standard　samples　with　different　concentration.　For　the　first　nine　samples,　the　measured　relative　integral　optical　density　increases　linearly　with　hCG　concentration　with　R2　=0.9975　and　a　line　equation　is　derived.　Based　on　the　linear　relation,　the　hCG　concentrations　of　another　five　samples　are　measured,　which　are　strongly　correlated　with　standard　concentrations　with　R2　=0.9914.　These　results　indicate　the　good　linear　response　property　and　accuracy　of　the　developed　method,　respectively.　©2010　IEEE.