Single molecule magnets(SMMs)with large magnetic anisotropy energy(MAE)have great potential applications in magnetic recording.Using the first-principles calculations,we investigate the MAE of 5d transition metal-porphyrin-based SMMs by using the PBE and PBE+U with different U values,respectively.The results indicate that W-P,Re-P,Os-P,and Ir-P possess the considerably large MAE among 5d TM-P SMMs.Furthermore,the MAE of 5d TM-P can be facilely manipulated by tensile strain.The reduction of the absolute value of MAE for Ir-P molecule caused by tensile strain makes it easier to implement the writing operation.The decreasing of the occupation number of minority-spin channels of Ir-dx2-y2 orbital leads the MAE to decrease when the tensile strain increases.