Abstract: To meet the need for service in ultra deep, extremely-thick and hi-pressure gypsum-salt layer with geodetic dip angle, the non-API Φ265.13 mm×22.00 mm TP155TB casing with transversal impact toughness bigger than 80 J is developed. Summarized here in the article are the general design principle, the thread type and the design requirement for the material properties. And the key points concerning the manufacturing process for the casing are analyzed, the actual quality level is checked, and the actual application status is described. The TP-FJ straight-connection premium joint with metallic sealing surface is used for the casing. And due to the graduated string structure design of the Φ244.5 mm casing and the sufficient clearance, the smoothly entering the original 311.20 mm well head, and the cementing quality are guaranteed.