The present invention provides a method, network side device and user equipment of variable bandwidth. The method includes: configuring a first type carrier and a second type carrier, wherein a chip rate of the first type carrier is 3.8Mcps, a chip rate of the second type carrier is P*3.84Mcps, and P is smaller than 1 and larger than 0; using the first type carrier and/or the second type carrier for communication. In this way, since the chip rate of the second type carrier is low and occupied bandwidth is small, the second type carrier may be suitable for non-standard bandwidth, thus utilization efficiency of bandwidth may be improved and waste of the bandwidth may be reduced.