The purpose of this study was to observe its in vitro inhibitory effect on human thyroid cancer cell line SW579 through PI3K-Akt pathway. In this study, the survival of cells and the inhibitory effect of gardenia tea extract (GTE) on SW579 cancer cells were firstly observed by MTT method. Further qPCR experiments were used to observe mRNA expression in SW579 cancer cells. The active compound composition in the GTE was then also determined by HPLC. The experimental results showed that GTE had almost no effect on normal primary thyroid cells and had no toxic effect, but GTE could significantly inhibit the proliferation of SW579 cancer cells. The detection of mRNA expression in SW579 cancer cells showed that GTE could upregulate the expressions of Bax, caspase-3, caspase-8 and caspase-9 and down-regulate the expressions of Bcl-2, Bcl-xL, PI3K and Akt in SW579 cancer cells. The chemical composition test showed that GTE mainly contains three compounds, namely rutin, quercetin and phloretin. It can be seen that gardenia tea can regulate the PI3K-Akt pathway of SW579 cancer cells through the effective active substances contained in it, and exert its anti-cancer effect. It is a health-care tea with good anti-cancer effect.