The invention provides a method for realizing RLC service data cell submitting in order. In the process of switch, a terminal works out the discontinuity point information of a SDU list according to received controlling information. The received SDU from a source base station and an object base station is carried out taxis according to the discontinuity point information. So an ordinal SDU list issubmitted to a high level. The SDU taxis of the invention can be finished at the RLC layer of the terminal. The PDCP layer of the terminal need not carry out taxis again. So, compared with the priorSDU taxis proposal, the invention eliminates the step of the SDU taxis carried out at the PDCP layer of the terminal. The complex degree of the terminal is reduced.