Trivalent chromium existing in wastewater from the dye plants is in complex state and its structure is very stable when coordinated with organic azo compound ligands. The conventional methods，such as neutralization-flocculation are not very effective for removing the Cr-complexes in three kinds of wastewater; black，yellow and orange wastewater. The results show that temperature and acidity are the two main factors influencing the thermodynamics stability of the complex chromium ion. For yellow or orange chromium complex，their structure could be destroyed by means of heating the wastewater raise its temperature or acidification. But for black chromium complex，its structure is more stable，it must be heated to higher temperature and be acidified simultaneously. The structure of black chromium complex could be destroyed efficiently. Complex chromium ion could be dissociated，and the free chromiumion could be removed easily via neutralization and precipitation in case of lime emulsion. Therefore，by means of such procedures as acidification，preheating, neutralization and flocculation，these complex chromium ions at high concentration can be destroyed and removed completely. The chromium content in the wastewater is lower than 1.0 mg/L after treatment，can meet the demand of heavy metal dischargestandard.