By analyzing the interaction effect between SiO32- and the main taste sensation， the internal mechanism of SiO32- affecting the taste quality of tea soup was explored. The study showed that with the increase of SiO32- mass concentration， the sweetness intensity of tea soup increases， the intensity of umami， bitterness and astringency decreases， and the overall taste quality of tea soup decreases. The decreased content of catechins， tea polyphenols， amino acids， epigallocatechin gallate （EGCG） and Ca2+， K+， Mg2+ plasma leach in tea soup is the reason why SiO32- leads to the decrease of taste quality of tea soup. The results showed that SiO32- could enhance the taste of sodium glutamate solution and sweet taste of sucrose solution， and weaken the bitter taste of caffeine solution and the bitter and astringent taste of EGCG solution， with obvious taste interaction effect. It is recommended that water containing SiO32- （＜48 mg/L） should be used for daily brewing of black tea.