Abstract: In this study, a special pulse planting apparatus was developed to form the chromium electrodeposits on a cast iron piston ring by direct current electroplating and a pulse current electroplating respectively in standard chromium bath, and the microstructure and microhardness of chromium electrodeposits were determined using optical microscope. The results show that the pulse current frequency greatly affects the microstructure and microhardness of chromium electrodeposits, the thickness and microhardness increase with the increase in pulse current frequency, and the grain is fined to form texture without pores and cracks. However, the cracks appear in hard chromium electrodeposits when the pulse frequency increases to 1.5Hz.