The invention discloses an ultrahigh pressure high-temperature needle valve which mainly comprises a valve body, a valve needle rod, a roll ball, a threaded rod, a handle, a fluid inflow channel, a fluid outflow channel and a sealing ring. The handle (7) is connected with the threaded rod (4), an I-shaped groove (10) is machined in the lower end of the threaded rod, a vertical hole (11) is formed in the valve body (1), the valve needle rod (2) of a clamping and guiding type is arranged in the vertical rod and is clamped into the I-shaped groove (10) of the threaded rod, the roll ball (3) is embedded between the valve needle rod (2) and the I-shaped groove (10) of the threaded rod, the sealing ring (8) is arranged between the valve needle rod and the vertical hole, a trapezoid pad (12) is arranged on the upper portion of the sealing ring, a valve needle point (14) and the valve body (1) are in metal hard sealing, and the valve body (1) is provided with the fluid inflow channel (5) and the fluid outflow channel (6). The ultrahigh pressure high-temperature needle valve can be applied to ultrahigh pressure experiment conditions, a valve needle is flexible in opening and closing, no rotary friction exists in the sealing cone of the valve body, the valve needle rod and the threaded rod are independent of each other, machining difficulty is reduced, the valve needle rod is convenient to replace after being abraded, and materials are saved.