The onion model summarizes the competency characteristics as a hierarchical structure from the inside out, the core of which is motivation, and then expands into personality, self-image and values, social role, attitude, knowledge and skills in turn. The more outward, the easier it is to cultivate and evaluate; The deeper you go, the harder it is to evaluate and obtain. Motivation is the internal driving force to push individuals to take action to achieve their goals; Personality is the way, tendency and characteristics of an individual's response to the external environment and various information. Self-image refers to the individual's view and evaluation of himself; Social role is an individual's understanding of a set of codes of conduct accepted and considered appropriate by his social group or organization; Attitude is the result of externalization of individual self-image, values and social roles. Knowledge is the fact and experience information that an individual has in a specific field; Skills are the ability of individuals to use knowledge in a structured way to complete a specific job. Generally speaking, the outermost knowledge and skills of "onion" are equivalent to the water part of "iceberg"; The innermost motivation and personality of "onion" is equivalent to the deepest part of the underwater "iceberg"; The self-image and role in the middle of "onion" is equivalent to the underwater shallow part of "iceberg". Compared with iceberg model, onion model is essentially the same, and both emphasize core quality or basic quality. The evaluation of core quality can predict a person's long-term performance. Comparatively speaking, onion model highlights the hierarchical relationship between potential quality and apparent quality, and can explain the relationship between quality better than iceberg model.