Abstract: The suction embedded plate anchor (SEPLA) is a new foundation to moor floating structures in deep water. Loss of embedment during keying has a significant effect on the design capacity. The envelope analysis method of plastic limit is adopted to simulate and analyze the embedment loss and the capacity of the keying process of SEPLAs, taking into account of the interactions of anchor chain, soil and plate anchor. The effects of varying padeye offsets and mudline angle of anchor chain on the embedment loss, inclination and capacity of the plate anchor are studied, and they are verified by the data of centrifuge experiments. The results from simulations show that the embedment loss of SEPLA decreases with the increase of padeye location offset towards the bottom of the anchor. The capacity of the plate anchor keeps stable when the eccentricity ratio of e_p/e_n is less than 0.1. When e_p/e_n is greater than 0.1, the bearing capacity of plate anchor significantly decreases. Besides, a better result of the bearing capacity can be yielded under the condition of a smaller mudline angle of the anchor chain with a smaller rotation angle.