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Aiming to meet the technical requirements of largeload helicopter, the spherical plain bearing of its rotor system has better antiwear capability, wearreduction and high bearing capacity in the complex working environment, so as to improve the life performance index of the bearing. A selflubricating spherical plain bearing used in the rotor system of a new type helicopter with large load was studied. CrDLC and WDLC film coating, were prepared on the surface of 9Cr18 inner ring substrates of spherical plain bearing by unbalanced magnetron sputtering. The microstructure, friction and wear properties and wear scar morphology of two kinds of thin film coatings were tested and analyzed by scanning electron microscopy, threedimensional topography, balldisk friction and wear tester and low speed heavy load friction and wear tester. The results showed that the friction coefficients of the two film coatings were increased gradually at the beginning of the friction stage. With the progress of the friction process, the friction coefficients tended to be stable and kept fluctuating in a certain range. Compared with 9Cr18-CrDLC specimens, 9Cr18-WDLC specimens had shorter stability time of friction coefficient, more stable overall friction process and lower friction coefficient, showing better friction performance. Compared with 9Cr18-CrDLC specimens, the wear process of 9Cr18-WDLC coating and selflubricating liner was relatively stable, the friction coefficient fluctuated in a small range, the overall wear scar was shallow, the overall wear volume was small, showing good wear resistance. The tribological properties showed that WDLC film coating had better wear resistance and antiwear properties for 9Cr18 substrate material. 