The　effects　of　concentration　and　type　of　anions　on　aggregation　of　Congo　red　in　solution　were　studied　with　UV-Visible　spectroscopy.　And　the　influence　of　anions　on　the　complex　of　Congo　red　and　oat　beta-glucan　was　further　studied.　The　results　showed　that　the　maximum　absorption　wavelength　of　Congo　red　in　aqueous　solution　shifted　toward　the　shorter　wavelength,　and　the　absorbency　lowered　considerably　with　increasing　ionic　concentration.　There　was　a　significant　linear　correlation　between　logarithm　of　anion　concentration　and　the　maximum　absorption　wavelength,　with　the　peak　absorbance,　and　the　absorbance　at　499　nm.　The　influence　of　anions　on　aggregation　of　Congo　red　was　in　accordance　with　Hofmeister　series,　indicating　that　hydrophobic　interaction　is　an　important　driving　force　for　Congo　red　molecules　to　assemble　into　micelles.　As　for　the　complexation　of　Congo　red　and　oat　beta-glucan,　when　the　concentration　of　anions　exceeded　the　first　critical　concentration,　the　micelle　of　Congo　red　began　to　form　and　then　combined　to　beta-glucan.　The　absorption　peak　of　the　complex　presented　at　556　nm.　When　the　concentration　of　anions　exceeded　the　second　critical　concentration,　the　complex　was　developed　into　supramolecular　structure　through　aggregation　of　Congo　red　micelles　on　Congo　red/beta-glucan　complex,　which　resulted　in　the　shift　of　absorption　peak　toward　583　nm.　And　the　presence　of　Mie　scattering　effects　at　the　longer　wavelength　indicated　the　formation　of　larger　supramolecular　structure.　The　effect　of　anions　on　the　above　supramolecular　structures　also　followed　the　order　of　Hofmeister　series,　showing　that　the　aggregation　of　Congo　red/beta-glucan　complex　into　supramolecular　structure　was　mainly　driven　through　hydrophobic　interactions　between　Congo　red　micelles　on　the　complex.　The　research　indicated　that　ions　had　an　important　effect　on　the　aggregation　of　Congo　red　and　the　interaction　between　biopolymers　and　Congo　red.