Abstract: A puncture needle assembly (1000) and a puncture system (100) are provided. The puncture needle assembly (1000) includes a needle holder (1100) and a needle (1200). The needle holder (1100) comprises a channel axially extending therethrough. The channel has a sidewall, at least a part of which is provided by a conductor (1110). The needle (1200) has a proximal end portion extending in the channel and electrically connected to the conductor (1110). The puncture system (100) includes the puncture needle assembly (1000) and a dilator (2000). The dilator (2000) includes a dilation catheter (2100) and an optional conductive biasing member (2200) disposed on the dilation catheter (2100). Even when a distal end of the needle (1200) is hidden in the dilation catheter (2100), the conductive biasing member (2200) can still establish an electrical connection between the needle and the blood outside thereof.