This study investigates the empirical research on the cross-market liquidity correlation of Taiwan 50ETF, index futures and index options, using data from the Taiwan market from 2010 to 2019. Four liquidity measures are used to explore the impact of liquidity across markets in the study: proportional bid-ask spread, proportional effective spread, volume, and dollar volume. The results of the study found that the liquidity of Taiwan index futures and index option has significant on the liquidity of Taiwan 50 ETF, and the influence of Taiwan index futures and index option on the liquidity of Taiwan 50 is also significant by using common liquidity factors. This means that the cross-market liquidity of Taiwan’s stocks, futures and options are interrelated and affect each other.