In order to resolve the problem that the heterogeneous is serious and the effect of water flooding is poor of ultra heavy oil reservoir in Lu-keqin oil filed，through the laboratory experiment and field experimentation, the foam ability, stability, salt-resistance and displacement effect of foam system was researched，and the foaming process was also tested. The results showed that，in the condition of high temperature(80℃) and high salinity(160000 mg/L)，the foaming rate of XHY-4 foam system was greater than 600%，and the half-life period was greater than 600 seconds，and the core flooding experiment indicated that the XHY-4 foam system could improved oil recovery by 15% with the injection of air-liquid alternation. Field test of nitrogen foam showed that the injection of gas-liquid alternation could form bubbles in the formation，the dominant channel of water flooding could be effectively plugged，which would reduce producing water and increase oil. The success of injection test has provided strong technical support for foam flooding pilot test of ultra deep heavy oil reservoir in Lu-keqin oil filed.