A wearable injection device includes: a driven unit； a microneedle injection patch having an injection therein and located on a side surface of the driven unit； and a wearable loop having two ends connected to the two end sides of the driven unit, respectively； wherein the driven unit has a first electrical property and the wearable loop has a second electrical property at a section opposite the driven unit； wherein the microneedle patch includes a microneedle array connected to the injection and attached on a skin of a biological limb, and the wearable loop surrounds the biological limb, and a direct current resulted from the first electrical property of the driven unit and the second electrical property of the wearable loop leads the injection injected into the biological limb via the microneedle array.
