This study aims to determine the effect of the Covid-19 pandemic on the liquidity of stock trading on the Indonesia Stock Exchange. Stock trading liquidity is representing by the LQ 45 index and the SMC Liquid index. This study uses the event study method, using before and after the announcement of Covid-19 for the first time by the Indonesian government. The data processed consists of weekly data LQ 45 index and SMC Liquid index period September 2019 to August 2020. Data processing using SPSS statistics software. The results concluded that the Covid-19 pandemic had a negative and significant effect on the LQ45 index. The Covid-19 pandemic also had a negative and significant affected on the SMC Liquid index.