A method for processing Voice over Internet Protocol (VoIP) packets is provided. The method includes: determining if the arrived VoIP packet arrives out of order according to a sequence number of the arrived VoIP packet and a sequence number of a preceding VoIP packet of the arrived VoIP packet; determining whether the buffer has a packet having a same sequence number as the arrived VoIP packet if the arrived VoIP packet arrives out of order; calculating the difference between the sequence number of the arrived VoIP packet and that of the preceding VoIP packet if the buffer has no such packet having the same sequence number as the arrived VoIP packet; and counting a number of pseudo packets needed to be inserted into the buffer according to the calculated difference and generating and inserting the number of pseudo packets into the buffer.