Abstract: The expansion of single- particle transition operator（ defined as the product of creation and annihilation operator,namely a＋iajin single- particle state is obtained through the form of single- operator in occupation particle number representation,and the commutation relations for transition operator and creation（ annihilation） operator are also given,then based on these conclusions,the form of general two- and n- particle operators in occupation particle number representation can be derived succinctly without distinguishing the statistical property of identical particle system.

Key words: second quantization, occupation particle number representation, general operator, transition operator