Light-emitting　diode　(LED)　modules　can　be　flexibly　disassembled　and　assembled　and　have　inherent　advantages　in　large-area　lighting　applications.　In　this　paper,　an　efficient　method　is　proposed　to　design　an　LED　freeform　lens　array　for　direct　lighting　based　on　an　adjustable　Cartesian　candela　distribution.　The　Cartesian　gradient　candela　distribution　(CGCD)　is　adjusted　and　determined　through　the　initialized　design　of　a　single　freeform　lens　and　a　diffuser　plate.　The　layout　of　the　LED　lens　array　can　then　be　optimized　by　controlling　the　semi-angle　of　the　light　intensity　distribution　(SALI).　A　design　example　shows　that　the　uniformity　of　the　lens　array　increases　by　11.63%　through　only　a　two-round　iterative　optimization.　Both　the　simulation　and　experimental　results　are　discussed　to　verify　the　proposed　design.　The　freeform　lens　array　is　expected　to　expand　the　applications　of　mini-　or　micro-LED　devices.　©　2019,　©　2019　Informa　UK　Limited,　trading　as　Taylor　&　Francis　Group.