The　aim　of　this　paper　is　to　extend　the　concept　of　the　solidarity　value　to　interval-valued　(IV)　cooperative　games　and　develop　a　fast　and　simplified　method　for　computing　the　IV　solidarity　values　for　a　special　class　of　IV　cooperative　games　under　some　weaker　conditions.　In　the　method,　we　find　a　size　(or　coalition)　monotonicity-like　condition　so　that　we　can　compute　the　IV　solidarity　values　of　a　special　class　of　IV　cooperative　games　via　determining　their　lower　and　upper　bounds　by　utilizing　the　lower　and　upper　bounds　of　the　IV　coalitions＇　values,　respectively.　In　addition,　some　important　and　useful　properties　of　IV　solidarity　values　are　discussed　and　the　feasibility　and　applicability　of　the　method　proposed　in　this　paper　are　verified　with　numerical　examples　as　well　as　comparison　analysis　with　existing　methods　is　conducted.　©　2018-IOS　Press　and　the　authors.　All　rights　reserved.