To　study　the　quantitative　influence　and　action　mechanism　of　structural　size　and　fiber　volume　fraction　on　the　splitting　tensile　strength　of　basalt　fiber　reinforced　concrete　(BFRC)　at　extreme　low　temperature,　four　sizes　(side　lengths　of　70,　100,　150,　and　200　mm)　and　four　fiber　volume　fractions　(fraction　range　of　0%　~　0.　5%)　of　BFRC　cubic　specimens　were　designed　for　static　splitting　tensile　failure　tests　at　room　and　low　temperatures　(temperature　range　of　20　~　-　90　℃).　The　experimental　results　show　that　all　the　splitting　tensile　strengths　of　different　type　of　concrete　increase　linearly　with　the　decreasing　temperature　(with　a　maximum　increase　of　nearly　130%),　showing　a　significant　low-temperature　strengthening　effect.　The　incorporation　of　basalt　fibers　can　slightly　improve　the　low-temperature　strengthening　effect　of　splitting　tensile　strength.　All　the　splitting　tensile　strengths　of　BFRC　with　different　fiber　volume　fractions　show　a　certain　fiber　reinforcement　effect,　which　can　be　enhanced　with　the　increase　of　volume　fraction.　At　extreme　low　temperature,　the　dominant　failure　mode　of　basalt　fiber　changes　from　pull-out　failure　to　rupture　failure,　which　can　cause　the　enhancement　of　fiber　reinforcement　effect　with　the　decreasing　temperature.　The　size　effect　on　splitting　tensile　strength　increases　with　the　decreasing　temperature,　while　the　addition　of　basalt　fibers　can　effectively　weaken　the　size　effect　(with　maximum　weakening　degree　of　25.　8%).　This　study　provides　an　effective　reference　for　the　applications　of　BFRC　in　engineering　structures　exposed　to　extreme　low-temperature　environments.　©　2025　Harbin　Institute　of　Technology.　All　rights　reserved.