Provided in the present invention is a composition of detection agents for living cells especially epithelial tumour cells the composition contains 0 5% folic acid 0 10% folic acid composite 0.01 5% methylene blue 0.1 10% sugar reducing agent 2 6% acetic acid and 3 95% water. Also provided in the present invention is a preparation method for the composition of detection agents and kits containing the composition of detection agents.