Disclosed is a plane array unfolding mechanism based on square units, comprising a plurality of square units which are vertically and horizontally combined with a cross quadrature connecting rod, an upper layered connecting rod, a right layered connecting rod, and a left layered connecting rod respectively via a cross layered connecting rod. The square unit mechanism, with the cross layered connecting rod as the center, is respectively connected with one end of each of the four T-shaped rods. The four T-shaped rods are connected with a right angle connecting rod and a layered right angle connecting rod. The square unit mechanism features less categories of the components forming the mechanism and simple structure. The mechanism is stably unfolded during the unfolding process with little impact and high repeatability. Moreover, the mechanism is simple to process and easy to assemble with small error. The whole system only has one single degree of freedom. The mechanism adopts a minisize motor to drive, thereby being easy to drive and control. The plane array unfolding mechanism based on square units of the utility model is particularly applicable to the satellite antenna unfolding system having large area of expansion and contraction, and can also be applied to the fields of handicrafts and building materials.