The invention relates to injection molding equipment, in particular to visual high-voltage direct-current cable flexible joint injection molding equipment for experiments. The problems that the whole process of polyethylene filling and flowing cannot be visually observed by means of existing injection molding equipment, and consequently design of a mold and selection of extruding parameters cannot be correctly guided according to the flowing process of polyethylene, the preparation efficiency of flexible joints in actual production is low, and the product quality is not high and unstable are solved. A flexible joint mold is transparent and is horizontally placed in a constant-temperature oil bath tank, and two opposite side walls, in the length direction, of the constant-temperature oil bath tank are each provided with a glass observation window; and an extruder is arranged on the outer side of the constant-temperature oil bath tank, and a discharging opening of the extruder communicates with an inlet of an extrusion molding channel on the flexible joint mold. The visual high-voltage direct-current cable flexible joint injection molding equipment is used for simulating molding and insulating manufacturing of the flexible joint mold.