The invention discloses a high-temperature and high-pressure ball valve. The high-temperature and high-pressure ball valve comprises a valve body, wherein a valve seat hole is formed in the valve body; a compensatory spring, an upper valve seat, a valve ball, a lower valve seat and a plug screw are sequentially arranged in the valve seat hole from inside to outside; the lower valve seat, the valve ball, the upper valve seat and the compensatory spring are mounted in the valve seat hole in a pressed manner by the plug screw; a connecting rod which is connected with the valve ball is further arranged in the valve body; an axial opening A and an axial opening B are symmetrically formed in two sides of each of two ends of the valve body; an axial opening P is formed in the plug screw; a radial through hole and an axial through hole are formed in the lower valve seat; two ends of the radial through hole are respectively communicated with the axial openings A and the axial openings B; the axial through hole is communicated with the axial opening P; and an L-shaped oil opening is formed in the valve ball, and corresponds to the radial through hole and the axial through hole of the lower valve seat so as to form a two-position and three-port valve. The high-temperature and high-pressure ball valve is small in size, compact in structure, small in occupied mounting space, reliable in sealing and suitable for high-temperature and high-pressure situations such as petroleum and natural gas underground flooding systems and power plants.