Onion water soluble polysaccharides were extracted from fresh onion with hot water by orthogonal design.The effects of extraction time,extraction temperature,water-to-solid ratio and extraction time were studied.The experiment was carried out to determine optimal technics parameter of extraction.The results showed that the optimal condition was determined as extraction time of 3.0 hours,extraction temperature of 80 ℃,water-to-solid ratio of 1∶12(m∶V) and extraction times of 3.Under this condition,the test content of onion water soluble polysaccharides was 3.697%.