The invention discloses a closed arteriovenous puncture trocar and aims to provide a closed arteriovenous puncture trocar adopting the following structure. According to the technical scheme, the trocar is characterized by comprising a puncture needle and a casing, wherein the casing comprises a head provided with a soft needle tubing and a casing body provided with a passage, the casing body is provided with a switch for controlling opening and closing of the passage, a cavity communicated with the passage is formed in the switch, and an elastic sealing element is fit in the cavity in a sealed manner. With the adoption of the structure, compared with the prior art, the closed arteriovenous puncture trocar has the advantages as follows: the switch for controlling opening and closing of the passage is arranged to open and close the trocar conveniently and stably, the cavity communicated with the passage is formed in the switch, the elastic sealing element is fit in the cavity in the sealed manner, a needle can directly penetrate through the elastic sealing element to enter the cavity, that is, pre-flush exhaust and input of normal saline after dialysis can be directly performed on the inner cavity of an instrument.