A preparation method for medical porous tantalum implant material is provided, which includes mixing polyethylene glycol aqueous solution and tantalum powder to form tantalum slurry, casting the tantalum slurry into an organic foam body through vibrant pressurization, and going through steps of drying, degreasing, vacuum sintering and thermal treatment to obtain the porous tantalum. The solution is a 2-8 wt% polyethylene glycol aqueous solution, the frequency of vibration is 20-80 times/min, the thermal treatment is performed under 10 -4 -10 -3 Pa of vacuity and the temperature is increased to 800-900°C at a rate of 10-20°C/min and keeping the temperature for 240-480 minutes, then decreased to 400°C at a rate of 2-5°C/min and keeping the temperature for 120-300 minutes, and cooled down to the room temperature naturally in the furnace. Accordingly, the porous tantalum made by the method of the present invention is a suitable for medical implantation as an alternative support of bony tissue, and assured good biocompatibility and mechanical properties. Furthermore, the reagents and the organic foam body, which are can be decomposed and resulting no residue during sintering, are used to guarantee the bio-safety of the medical porous tantalum implant material.