Tungsten carbide (WC) hard metals are universally used in industrial fields owing to their superior properties, and the machining accuracy of WC products is playing an important role in their service performance. However, how to achieve a balance between high accuracy and processing cost according to different applications is a key engineering issue. Thus, it is necessary to reveal the material removal characteristics of such difficult-to-cut hard metals. In this article, ultra-precision grinding characteristics of WC-Ni hard metals were investigated based on the wafer rotation grinding method using #120, #600, #2000, and #12000 diamond cup wheels as coarse, semi-finished, fine, and finish grinding wheels, respectively. A polished sample was taken for comparison. The optical surface profilers, scanning electron microscope, and atomic force microscope were employed for checking surface topographies, surface morphology, and cutting depth. An ultra-smooth and defect-free WC-Ni surface with less than 2 nm Ra and the average cutting depth of about 10 nm can be obtained using a #2000 diamond wheel, which can replace polishing and satisfy the requirements of most high-performance applications. This study provides useful observations for ultra-precision manufacturing of hard metal products. [ABSTRACT FROM AUTHOR]