An expandable implant of a minimally invasive surgery contains a body, a positioning post, two first connecting sets, two second connecting sets, and two expanding pieces. The body includes two seats and an adjusting knob. The positioning post inserts into the body and includes one side contacting with the adjusting knob and another side having a conical member. The two first connecting sets couple with the two seats, and each first connecting set has two first rods coupling with a respective one of the two seats. The two second connecting sets connects with the positioning post, and each second connecting set has two second rods coupling with the positioning post. Each expanding piece axially connects with one of the two first rods of each first connecting set and one of the two second rods of each second connecting set.