Abstract: Fire soaking production is an advantageous thermal production technology fast developed in recent years. This technology requires cement slurry to have the thermal stability above 550℃ and resistance to CO₂ corrosion, such as GWC-500S, a phosphoaluminate cement which was developed by adding phosphate, alumina powder, corrosion resistant agent and activator into an aluminate cement. A liquid filter loss reducer GWF-500L and an inorganic acid retarder GWR-500S have also been developed for use in the cement. A cement slurry was developed with these materials and the set cement was tested using XRD at 50℃, 300℃ and 600℃. Hydrates of the cement and their changes with temperature were analyzed. Set cement calcinated at 600℃ was analyzed using SEM for its profile. Changes in the strength of the phospho-aluminate cement after calcination at 550℃ for 7 d were evaluated. Resistance to CO₂ corrosion of set cement at 120℃ and a CO₂ partial pressure of 6.9 MPa was evaluated. It is understood through these studies and evaluations that the phospho-aluminate cement slurry has thickening time adjustable between 40℃ and 100℃, API filter loss of less than 50 mL, and good rheology. The set cement has the advantages such as:resistance to high temperature to 550℃, resistance to CO₂ corrosion, adjustable density, moderate thickness, good stability, and good compatibility with drilling fluids and spacers. The cement slurry has been successfully tried on well Yingshi X in a fire soak test block in XX oilfield. Laboratory experiments and field application prove that the phospho-aluminate cement slurry satisfies the needs for fire soak well cementing.