A method for switching video pictures among participants during a video conference session, the method comprises: Obtaining correspondence relations between participants and venues; Receiving a voice signal during the video conference session and determining whether a participant is called based on the received voice signal; Finding, when determining the participant is called, a venue corresponding to the called participant according to the correspondence relations; and Switching the video pictures to the venue corresponding to the called participant; wherein the steps of receiving a voice signal during the video conference session and determining whether a participant is called based on the received voice signal comprises: receiving, by a Multipoint Control Unit, the voice signal during the video conference session; and determining, by the MCU, through voice recognition technology whether the participant is called based on the voice signal; and wherein before finding the venue corresponding to the called participant according to the correspondence relations, the method comprises: determining whether the called participant is involved in the correspondence relations; obtaining the venue corresponding to the called participant once the called participant responds to the call, if the called participant is not involved in the correspondence relations, and recording a correspondence relation between the called participant and the venue corresponding thereto. Obtaining correspondence relations between participants and venues; Receiving a voice signal during the video conference session and determining whether a participant is called based on the received voice signal; Finding, when determining the participant is called, a venue corresponding to the called participant according to the correspondence relations; and Switching the video pictures to the venue corresponding to the called participant; wherein the steps of receiving a voice signal during the video conference session and determining whether a participant is called based on the received voice signal comprises: receiving, by a Multipoint Control Unit, the voice signal during the video conference session; and determining, by the MCU, through voice recognition technology whether the participant is called based on the voice signal; and receiving, by a Multipoint Control Unit, the voice signal during the video conference session; and determining, by the MCU, through voice recognition technology whether the participant is called based on the voice signal; and wherein before finding the venue corresponding to the called participant according to the correspondence relations, the method comprises: determining whether the called participant is involved in the correspondence relations; obtaining the venue corresponding to the called participant once the called participant responds to the call, if the called participant is not involved in the correspondence relations, and recording a correspondence relation between the called participant and the venue corresponding thereto. determining whether the called participant is involved in the correspondence relations; obtaining the venue corresponding to the called participant once the called participant responds to the call, if the called participant is not involved in the correspondence relations, and recording a correspondence relation between the called participant and the venue corresponding thereto.