Pu-erh　tea　has　gained　more　and　more　popularity　and　attracted　much　attention　for　its　various　biological　effects.　The　objective　of　this　study　was　to　determine　the　active　phenolic　compounds　and　the　biological　effects　of　15　differently　aged　Pu-erh　teas.　The　results　showed　that　43　active　phenolics,　containing　7　flavan-3-ols,　11　organic　acids,　and　esters,　3　proanthocyanidin　dimers,　2　benzotropolones,　and　20　flavonoid　glycosides　were　identified　based　on　high-performance　liquid　chromatography　coupled　to　electrospray　ionisation　and　quadrupole　time-of-flight　tandem　mass　spectrometry　(HPLC-ESI-QTOF-MS/MS).　In　particular,　2’-O-galloylhyperin　and　quercetin-3-O-p-coumaroyl-rhamnosyl-arabinosyl-hexoside　were　identified　from　constituents　of　tea　for　the　first　time.　The　15　Pu-erh　teas　exhibited　strong　DPPH　and　ABTS　scavenging　activity　in　a　concentration-dependent　manner　with　IC50　0.99–2.12　and　0.97–2.67　mmol　Trolox　equivalent　antioxidant　capacity/g,　respectively.　All　of　the　Pu-erh　teas　tested　significantly　inhibited　the　proliferation　of　SMMC-7721　cells,　in　a　dosage-dependent　manner.　Of　the　15　Pu-erh　teas　examined,　the　cake　tea　P6　had　the　strongest　effect　on　SMMC-7721　cells　with　IC50　=　65.88　±　3.53　µg/mL.　The　others　Pu-erh　teas　had　an　IC50　=　96–509　µg/mL.　Our　results　also　indicated　that　not　all　the　older　Pu-erh　teas　display　stronger　anti-activities　and　anti-cancer　than　the　younger　ones　and　the　youngest　Pu-erh　tea　did　not　possess　the　highest　level　of　active　components.　This　study　provides　useful　information　for　consumers　to　deeply　understand　the　chemical　constituents　and　bioactivity　of　Pu-erh　tea　preserved　for　a　long　time.　©　2017　Taylor　&　Francis　Group,　LLC.