Abstract: The configuration-bias-vaporization Monte Carlo simulation method developed by Yan et al . has been used to simulate the phase equilibria of AB random copolymers based on the close-packed Flory-Huggins lattice model. Random copolymers are represented as linear chains consisted of r A segment A and r B segment B with segment-segment attractive interaction energy parameters ε AA / kT=-1.0/T *, ε AB / kT=-0.8/T * and ε BB / kT=-0.6/T *. The phase diagrams of random copolymers with a chain length up to 200 segments are obtained. The corresponding critical points for different chain lengths with fixed chain composition are also calculated.