It is inadvisable to copy the essence of legal person in civil law to explain the nature of unit in criminal law, and then identify unit in criminal law on the basis of civil capacity for action or independent property and funds. Only eliminating normative factors in civil law thoroughly, and integrating the value of criminal law into unit's existence in practice, can interpret the nature of unit accurately. Therefore, unit in criminal law is the carrier of will, its essence is the group will, which is formed on interests as the inner core and organizational structure as the external guarantee. Accordingly, the criteria for judging qualification of a unit as criminal subject is:the group has a will relatively independent of its members and upper and lower units. It should start with the analysis of the unit's organizational structure, and focus on the power allocation and supervise balance mechanism of the unit.