Abstract: With progresses in oilfield exploration and development, more and more wells encountered casing deformation caused by geological or engineering reasons, which may seriously restrict production and EOR measures. Since diameters of borehole with casing deformation are reduced, mechanical tools for stratified fracturing operation may experience difficulties in passing through. In addition, stuck risks in intervals with casing deformation are high for these tools. Under such circumstances, conventional tools can hardly be used in stratified fracturing to achieve desirable performances. Therefore tools for fine stratified fracturing operation in wells with casing deformation have been developed. Based on detailed study on the structure and material of fracturing string, nozzles in integral flowing channel structure, cluster fracturing sleeves and other key tools, these fracturing tools are determined to have minor diameters, outstanding abrasion-resistance performances, high adaptability and other desirable features to fully satisfy demand for fracturing and fine stratification in wells with casing deformation. Field application results are satisfactory. Through fine stratification, EOR performances can be maximized. In the future, these tools can be applied more extensively.