A phylogenetic tree is a representation of the evolutionary histories of different species from which the gene tree is constructed from some specific sequence of copies of genes that are sampled from a group of species. For some biological events like gene Duplication (D), Horizontal Gene Transfer (T), Loss (L), and Incomplete Lineage Sorting (ILS), with the passage of time, the history of gene evolution and species evolution might show discord in most cases. Though many researchers do not account ILS event as discordance between a gene tree and species tree because, in theory, ILS is not a true “gene event” such as duplication or a transfer, since nothing “happens” to the gene during incomplete lineage sorting. But still, this phenomenon can lead to a gene tree differing from the species tree just like speciation acts on populations. Reconciliation is a process of resolving a disagreement between gene and species tree with the least possible evolutionary event costs. Addressing this problem (not accounting ILS event), we propose an efficient Pareto-optimal algorithm to reconcile a binary gene tree with binary species tree under Duplication, Transfer, Loss and Incomplete Lineage Sorting parsimony criterion, which is the extension of the previous Pareto-optimal algorithm developed by Libeskind-Hadas et al., 2014[12]. Through this research, it has been shown that how to properly cost DTL events considering ILS event and then give a fixed-parameter tractable (FPT) algorithm which calculates the most parsimonious Duplication (D), Horizontal Gene Transfer (T), Loss (L), and Incomplete Lineage Sorting (ILS) reconciliations. Comparing with the previous Pareto-optimal algorithm, the space complexity will remain the same after considering the ILS events. This is the first Pareto-optimal reconciliation algorithm to consider all of the four evolutionary processes driving tree incongruence.