Adding of phosphorus into wastewater would promete the growth of the water hyacinths ("Eichhornia crassipes"). Adding of the sediment of oxidation-pond did not inhibit but promoted the growth of the plant. When the phenol concentrations of the wastewater were above 350ppm, pH was below 3 or above 10 and the conductivities were above 4100 μ /cm, the water hyacinths would die in few days. the optimum growth conditions of the plant were: the phenol concentrations below 55ppm, pH 5-8 and conductivities below 1700 μ /cm. The toxic effect of the poisonous contents in the wastewater on plant growth was more serious under pH 9 than those under pH7. The poisonous contents could increase the toxic effect of pH and saltness, but could not increase that of phenol significantly. When the wastewater was filtered through activated carbon or degraded naturally, the toxicity decreased remarkably. The water hyacinth, "Thragmites australis" and "Alternathera philoxeroides" all had remarkable ability to purify the wastewater, but the purification effeciency decreased successively in series. The BOD_5 of the wastewater decreased from 211 mg/L to 60 mg/L in natural open water for 17 days, but only 10 days in the water hyacinth pond. The COD decreasing precess could express with the exponential function: CQD = A·e~(-B·D). The mean surface prification rate (Ps) of the static water hyacinth pond was 9.1 g COD/m~2d. The water hyacinth purifing dynamic simulation test with two ponds in series was classfied into three stages, the detention times were 18, 7 and 4 days respectively. They all obtained good purifing effects. The COD, BOD and other waste contents decreased obviously. The BOD/COD ratio of the influent and the effluents of pond 1 and pond 2 decreased gradually. The pH value of the two pond effluents nearing the neutral were lower than the influent. The bacteria numbers of the influent and the effluents of pond 1 and pond 2 decreased gradually in series. In the third stage of the dynamic test, the COD, phenol, oil and sulphur contents of the effluent of pond 1 were sometimes exceesed the water quality standards. But in most times, the pollution indexes of the effluents of pond 1 and 2 revealed that they were under the water quality standards. The COD removal constants (K) of pond 1 and pond 2 were 0.376 and 0.151, the surface purification rate (Ps) were 9.51 and 2.38 g COD/m~2d, the increased biomass (wet weight) of water hyacinths were 226 and 210 g/m~2d, the daily growth rate were 4.4 and 4.0, respectively. When the temperature of the air was in the field of 10-20 ℃, the COD removal rate (R) of pond 1 decreased as the daily mean temperature (T) decreased in the form: R = 87.70 lnT-200.15.