In order to provide helps for industrial applications,this paper studied the microstructures and properties of iron-base powder of different compositions. First,iron-based alloy coatings were prepared by plasma spray equipment,and then cracks on surface of coatings were tested by penetrant testing. Second,chemical compositions were tested by direct reading spectrometer,and then analysis the influences of chemical compositions on microstructures. last,Rockwell hardness and wear quantity of iron-base powder coatings were tested by Rockwell hardness tester and pin-on-disk wear testing machine,and then study the influences of microstructures on hardness and wear. Through above tests,we found that,firstly when the value of Creq/Nieq is 0.26,crack appears on the surface of coating. Secondly microstructures are influenced by the values of Creq and Nieq,so the matrix is mainly austenitic.Thirdly there is no linear relationship between Creq/Nieq of hardness and wear resistance,and the hardness of five iron-base powder is all above 40 HRC. Fourthly, the wear resistance of coatings increases with the increase of hardness, and the wear loss of Fe5 is only 3.65g,but when the hardness of iron-base powder reaches 59 HRC,wear resistance decreases. So,according to the above research,we can believe that the chemical compositions of the claddings determine microstructures,especially c content. When the carbon contents increase,hardening phase is formed in coatings,such as M,7,C,3,so hardness and wear resistance are higher. But,when the hardness reaches a certain value, the appearance of crack causes the hard phases spall, wear resistance decreases.