Abstract: School of Material Engineering;Soochow University;Suzhou;Jiangsu 215021The stability of lac pigment under different conditions such as temperature,pH value,metal ions,oxidants and reducing agents was investigated by spectrophotometric methods for the purpose of providing a theoretical basis for its utilization in dyeing of textiles.The results showed that the lac pigment color changed with the pH value of solution;and temperature had little influence on it in acidic condition;oxidant,reducing agent,and alkali were disadvantageous to its stability;Ca²⁺、Cu²⁺、Al³⁺、 Fe³⁺、Fe²⁺、Zn²⁺、Sn²⁺could complex with lac pigment,alter the color of pigment solution;lac-Fe²⁺complex was confirmed by infrared absorption spectrum.;China