We study the critical behaviour of the chiral phase transition of SU(3) lattice QCD with one species of staggered fermions in the strong coupling limit. We find a second-order phase transition which seems to be controlled by an effective action which is in the same universality class as three-dimensional O(2) spin models. In particular, we find for the exponent-delta, 0.18 < 1/delta < 0.25, in good agreement with the three-dimensional O(2) value, 1/delta = 0.21.