Abstract: The DCX cementing flushing evaluation simulator was developed to quantitatively analyze working mechanism of flushing fluid to filter cake at the permeable layers.The apparatus can not only simulate the cake forming process,but also simulate the flushing efficacy under the different operating conditions.With the device,a series of experiments were conducted to evaluate the flushing efficiency of two kinds of flushing fluids on cakes formed by two kinds of drilling fluids.The experimental results showed that:the flushing efficiency varied widely when influential factors changed,with the biggest disparity being 5.56%-7.76%.The best flushing program,which could ensure the cleanliness of annular interface,could be selected through comprehensive evaluation and data analysis.The apparatus offers a new means for analyzing the working mechanism of the flushing fluid and provides reliable experimental data for improving flushing efficiency.