The　retroreflection　coefficients　of　230　traffic　sign　retroreflective　sheetings　set　in　Beijing　test　site　of　Ministry　of　Transport　were　observed　continuously　for　thirteen　years.　The　prediction　models　of　attenuation　values　for　the　retroreflection　coefficients　of　traffic　sign　retroreflective　sheetings　with　different　colors　and　types　were　built.　The　attenuation　law　of　retroreflection　coefficient　with　set　time　was　analyzed.　Analysis　result　shows　that　the　prediction　models　of　attenuation　values　for　the　retroreflection　coefficient　of　white　types　I-III　retroreflective　sheetings　are　cubic　function,　logarithmic　function　and　cubic　function　models　respectively,　and　the　determination　coefficients　are　0.581,　0.732　and　0.559　respectively.　The　variation　amplitudes　of　attenuation　rate　for　retroreflection　coefficient　of　red　types　I-III　retroreflective　sheetings　are　16.0%,　28.0%　and　42.0%　respectively,　and　the　variation　amplitudes　of　attenuation　rates　for　retroreflection　coefficients　of　retroreflective　sheetings　with　other　colors　are　less　than　21%.　So,　the　quadratic　function　and　cubic　function　models　of　attenuation　values　for　retroreflection　coefficients　have　better　fitting　property,　there　are　significant　differences　among　attenuation　laws　of　retroreflection　coefficients　for　retroreflective　sheetings　with　different　colors　and　types,　and　the　attenuation　slows　down　with　increase　of　set　time.　©　2016,　Editorial　Department　of　Journal　of　Traffic　and　Transportation　Engineering.　All　right　reserved.