There are various project scheduling problems like single-mode resource constrained problem, multi-mode resource constrained scheduling problem, single-project and multi-project scheduling problem. Multimode Resource Constrained Project scheduling problem (MRCPSP) is NP-hard problem in which each activity has several non-preemptive execution modes. Each execution mode of an activity has a different resource requirement (renewable and non-renewable resource) and a related duration. On project scheduling problems with multiple execution modes, the genetic algorithm performed better than deterministic, bounded enumerative search methods. Various approaches and techniques have been applied for getting approximate optimized solution by some authors and scientists. These techniques have been discussed in this paper.