Four expansin protein sequences of Calotropis procera are extracted from UNIPROT database. Using FASTA sequences of these proteins e.g. CpEXPA1, CpEXPA2, CpEXPA3 and CpEXPA4, homology modeled structures are derived from SWISS-MODEL (Arnold, et al, 2006) evaluating by GMQE score. A phylogenetic tree has been built up with these sequences.