Tunable　multi-wavelength　polymer　lasers　based　on　two-dimensional　distributed　feedback　structures　are　fabricated　on　a　transparent　flexible　substrate　using　interference　ablation.　A　scalene　triangular　lattice　structure　was　designed　to　support　stable　tri-wavelength　lasing　emission　and　was　achieved　through　multiple　exposure　processes.　Three　wavelengths　were　controlled　by　three　periods　of　the　compound　cavity.　Mode　competition　among　different　cavity　modes　was　observed　by　changing　the　pump　fluence.　Both　a　redshift　and　blueshift　of　the　laser　wavelength　could　be　achieved　by　bending　the　soft　substrate.　These　results　not　only　provide　insight　into　the　physical　mechanisms　behind　cocavity　polymer　lasers　but　also　introduce　new　laser　sources　and　laser　designs　for　white　light　lasers.