In this paper, alloy with composition of MgMnAlZnCu was designed by using the strategy of equiatomic ratio and high entropy of mixing. The microstructure and mechanical parameters of the new high entropy alloy cooling in three conditions were studied. The alloy was prepared by induction melting and then it was cast in copper molds in air, water and salt water respectively. The microstructure and properties of alloy samples were examined by microhardness tester, XRD, TEM, SEM and testing machine for material strength. The results showed that the alloy was composed mainly of h.c.p and Al-Mn quasicrystal phases. The alloy exhibit high hardness (431HV-467HV) and high compression strength (428MPa-450MPa) at room temperature. The alloy was fragile and the strains were from 3.29% to 5.53%.