Abstract: In order to reduce the damage by drilling fluid to oil and gas formation during drilling,the temporary plugging technology for reservoir is usually selected and the key is that temporary plugging particle size reasonably matches the pore throat.The matching is difficult to grasp,thus affecting the reservoir protection.According to the drawback of traditional temporary plugging technology in application,the technology of mosaic agent-membrane agent synergistic interaction for reservoir protection was proposed.Mosaic agent XQ-3 and membrane agent DL-7 for reservoir protection were developed and selected based on the combination of traditional evaluation of drilling fluid and evaluation of sand core test piece.If both were compounded,the temporary blocking rate was 99.6% and the slicing core permeability recovery was 99.4%.Comparing with the traditional blocking technique,they were increased by 20.6% and 15.3% respectively,showing good synergistic interaction temporary blocking effect and stronger adaptability to different pores,which can be used as a new drilling fluid system for formation protection.