To　explore　the　compressive　behavior　and　corresponding　size　effect　of　concrete　columns　internally　reinforced　with　basalt　fiber-reinforced　polymer　(BFRP)　bars　and　stirrups,　twelve　geometrically　similar　columns　were　tested　under　axial　compression.　The　test　parameters　included　cross-sectional　shapes,　cross-sectional　diameters/widths　and　stirrup　ratios.　The　test　results　indicated　that　both　the　circular　and　square　BFRP　reinforced　concrete　(RC)　columns　presented　a　notable　size　effect　on　nominal　compressive　strength　and　ductility.　As　the　cross-sectional　size　varied　from　200　mm　to　600　mm,　the　nominal　compressive　strength　of　circular　and　square　columns　exhibited　maximum　decreases　of　11.0　%　and　19.1　%,　respectively,　while　the　maximum　decreases　of　ductility　index　were　66.2　%　and　16.7　%,　respectively.　Moreover,　increasing　the　stirrup　ratio　could　effectively　improve　the　confine-ment　efficiency　and　ductility　as　well　as　weaken　the　size　effect　on　nominal　compressive　strength　of　BFRP　RC　circular　columns.　The　accuracy　of　available　design　equations　was　significantly　influenced　by　the　confinement　effect　of　BFRP　spirals　in　circular　columns,　while　for　square　columns　the　specimen　size　was　the　most　important　factor.　Finally,　new　equations　were　derived　by　considering　the　confinement　effect　of　stirrups　or　size　effect　of　concrete,　and　these　equations　showed　satisfactory　accuracy　in　predicting　the　axial　load-carrying　capacity　of　BFRP　RC　columns.