Seal　oil　fatty　acids　are　the　important　natural　source　of　some　functional　fatty　acids,　for　example,　DPA,　EPA　and　DHA.　The　three　kinds　of　effective　components　(DPA,　EPA　and　DHA)　in　the　rough　finished　product　of　seal　oil　account　for　about　20%　of　the　total　content.　However,　the　healthcare　applications　using　seal　oil　fatty　acids　require　products　with　higher　purity.　To　meet　this　requirement,　it　is　necessary　to　selectively　enrich　the　content　of　the　effective　components　in　the　crude　product.　A　pilot　plant　VTA　wiped　film　molecular　distillation　unit　is　used　to　give　a　product　(residue).　The　seal　oil　fatty　acids　in　residue　have　a　higher　content　of　the　effective　components　(about　26%)　than　the　undistilled　material　with　a　content　of　about　20%.　Feed　flow　rates　and　evaporator　temperatures　are　varied　to　observe　the　resultant　of　the　purity　and　yield　of　DPA,　EPA　and　DHA　in　the　residue　and　the　residue　to　distillate　split　mass　ratio.　The　maximum　values　of　the　purity　in　the　residue　fraction　are　0.269　(301　degrees　C),　0.263　(310　degrees　C),　and　0.266　(317　degrees　C),　and　the　maximum　values　of　the　split　ratios　and　yields　occur　at　294　degrees　C　(1.392,　0.694),　299　degrees　C　(1.588,　0.727),　and　309　degrees　C　(1.380,　0.685).　Therefore,　there　is　a　trade-off　between　the　yield　and　purity　of　DPA,　EPA　and　DHA　in　the　residue.　The　higher　the　temperature　is,　the　higher　the　purity　but　the　lower　yield.　In　conclusion,　seal　oil　fatty　acids　can　be　successfully　purified　for　healthcare　applications　using　a　pilot　plant　wiped　film　molecular　distillation　unit　and　high　vacuum.