This paper studies a two-lane totally asymmetric simple exclusion processes with parallel update rule. The particles move with the same direction on the two lanes. When the particles are blocked by the front particles, they will try to change to the other lane with probability ps if the corresponding site on the other lane is empty. The 2-cluster mean field approach is generalized to the two-lane system, which successfully takes into account the correlation. It is shown that the results of the 2-cluster mean field approach agree with the simulation results well. The phase diagram of open boundary is constructed by using the analytical results of periodic boundary condition. The analytical results are in preferable agreement with the simulation results.