The invention discloses a constant-temperature type oil-air-cylinder single-point needle valve hot runner which comprises a cylinder body, a top cover, a conical bottom cover, a hot nozzle body, a piston and a heater. The top cover and the conical bottom cover are fixed to the two ends of the cylinder body correspondingly. A stepped piston hole is formed in the cylinder body. The outer wall of the piston is in a step shape, and the piston is slidably arranged in the piston hole. A sealed space is formed between the outer wall of the piston and the cylinder body, and another sealed space is formed among the outer wall of the piston, the cylinder body and the conical bottom cover. A through hole is formed in the axis position of the piston, and the hot nozzle body is arranged in the through hole and sleeved with the heater. The cylinder body and the conical bottom cover are each provided with a cooling circulating water channel. The cooling circulating water channel in the cylinder body surrounds the cylinder body. The cooling circulating water channel in the conical bottom cover surrounds the conical bottom cover. In this way, it can be guaranteed that a single-point needle valve hot runner system stably operates at the normal working temperature of a sealing system, and the single-point needle valve hot runner system is long in service life, high in efficiency and low in maintenance cost.