A pot experiment was conducted to study the effects of different water treatments (normal irrigation，light drough，moderate drought，and severe drought) on the quality，gas exchange and chlorophyll fluorescence characteristics of purple cabbage(Brassica campestris ssp. chinensis var. communis Tsen et Lee). The result showed that: (1) with the increasing extent and duration of drought stress，the maximal anthocyanin content, the soluble sugar, soluble protein and vitamin C contents of the purple cabbage leaves increased gradually under light drought stress, while decreased rapidly under both moderate and severe drought stress. (2) As compared with those under normal irrigation, the chlorophyll a, chlorophyll b, chlorophyll (a+b) and carotenoid contents all increased gradually under light drought stress, while decreased rapidly under both moderate and severe drought stress. (3) With the degree of drought treatment, the net photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r) all decreased gradually under light drought, moderate and severe drought stress, while water use efficiency (WUE) increased firstly and then decreased. (4) With the degree of drought treatment, performance index on absorption basis (PI_ABS) decreased rapidly under all drought stress, while absorption per active reaction centers(ABS/RC), trapping per active reaction centers(TR_O/RC), electron transport per active reaction center(ET_O/RC), dissipation per active reaction centers(DI_O/RC)all increased gradually under drought stress, trapping per excited crosssection(TR_O/CS), dissipation per excited crosssection (DI_O/CS) both decreased rapidly under all drought treatments. The maximum quantum yield of PSⅡ (ψ_PO), efficiency that a trapped exciton can move an electron into the electron transport chain beyond Q_A^-（ψ_O）, probability that an absorbed photon will move an electron into the electron transport chain beyond Q_A^-(ψ_EO) all decreased rapidly under all drought treatments. The value of relative variable fluorescence at Jstep (V_J) increased more than the value of the ration of fluorescence F_K to the amplitude F_JF_O (W_K), while the increasing of the maximum rate of reduction(M_O) stated that Q_A be restored. Those results suggest that under light drought treatment, the anthocyanin and photosynthetic pigment contents increased. Moreover, the photosynthetic rate and the quality of plant nutrition improved. It is worth popularizing and applying in the dry production of purple cabbages.