To extend the kind of diamond and solve the low life of diamond tools because of the insufficiency of holding force, the strip-shape diamond with more than 2.5 in length-diameter ratio and 0.81.0 mm in length is synthesized by optimizing FeNi based catalyst composition and using the technology in the China-type cubic anvil high pressure apparatus. Because of the unique morphology, the threshing phenomenon appearing in the using of diamond tools is controlled effectively. Furthermore, we find that the growth rate of strip-shape diamond is much faster than that of the conventional diamond. Strip-shape diamond morphology and catalyst composition around the growing diamond crystal are characterized by SEM and EDS. The results indicate that the facets of diamond crystal are elongated along 100 and 111 faces and catalyst compositions around the growing diamond crystal become segregated. On this basis, we illustrate the growth mechanism of strip-shape diamond.