In-situ crude oil emulsification often occurs in chemical flooding. Emulsification plays a positive role in enhancing oil recovery. Due to the complexity of pore-throat structure and remaining oil distribution，in-situ crude oil emulsification has its own characteristic. Based on the research results of crude oil in-situ emulsification in chemical flooding in recent years，the status and development trend were investigated from the in-situ emulsification mechanism of chemical flooding，rheology and stability of emulsion，emulsion seepage characteristic and improving oil recovery mechanism. The in-situ emulsification mechanism of crude oil and exploiting experience were analyzed from the field test of chemical flooding. The numerical simulation considering emulsification formation mechanism，emulsification degree and rheological property of emulsified crude oil，and the optimization design of chemical flooding injection scheme based on emulsification mobility control were the key research direction of chemical flooding in the future. It could provide theoretical guidance for the optimization of chemical agent and injection parameter of chemical flooding.