In order to solve the problem of plugging in Bohai oilfield，through measuring interfacial tension，washing oil efficiency and wettability reversal properties，the surfactant with better performance was selected，the extractant with good performance was optimized by measuring the oil washing efficiency of extractant. The emulsion type oil wash agent was prepared by combining surfactant and extractant，and the compatibility，stability and wash oil Efficiency was measured and oil washing mechanism were analyzed. The results showed that the single surfactant with the best oil washing efficiency for oil sands was OP-10，being of 29.4%.The better extractants were petroleum ether and xylene，and the oil washing efficiency of the two extractants to the oil sands reached up to 80%. After combining surfactants and extractant，the oil washing efficiency could be significantly increased to 95%.The developed emulsion detergent，composed of 2% xylene，8% petroleum ether and 2%OP-10，had good compatibility，stability，possessing good application prospects.