Abstract: A needle protection device and a safety needle assembly are described. The needle protection device comprises a connecting portion and a protection arm rotatable relative to the connecting portion. A pair of holding members are respectively formed on a proximal end portion of the protection arm and the connecting portion and configured to engage with each other in an unretreatable manner. A pair of positioning arms are respectively formed on the proximal end portion of the protection arm and the connecting portion and formed with at least one pair of complementary snap-fitting features. The paired snap-fitting features are configured to engage each other in a separable manner. The needle protection device and the safety needle assembly not only reliably prevents medical instruments from incurring accidental needle-sticks after use and ensures such medical instruments disposable, but also exhibits a simple structure and low costs.