Regarded　curve　sections　of　mountainous　expressway　as　research　object,　setting　method　and　procedure　of　advisory　speed　limit　signs　were　studied.　Speed　information　data　from　8　curves　were　collected　for　one　year.　Speed　difference　concept　was　figured　out　and　speed　difference　threshold　was　determined　by　linear　model.　The　value　of　advisory　speed　limit　was　determined　through　considering　operation　speed　and　design　speed.　Finally,　the　advanced　distance　of　advisory　speed　limit　sign　was　determined　considering　drivers＇　visual　characteristics　and　operation　speed.　Results　show　that　when　horizontal　curve　is　small　than　300　m,　advisory　speed　limit　sign　should　be　set　on　horizontal　curve　for　expressway.