A scheduling request method, network side device, terminal device and system, belong to the field of communications technologies. The method includes: configuring a first shared resource used for a scheduling request (SR), and sending first information to multiple terminal devices to notify of the first shared resource (101); receiving the SR on the first shared resource (102); allocating a second shared resource of uplink data to the multiple terminal devices, or allocating a dedicated resource of uplink data to at least one of the multiple terminal devices (103). The network side device includes: a configuration module, a receiving module and an allocation module. The terminal device includes: a receiving module, a request module and a sending module. The present invention avoids the waste of the uplink data resource, and improves a utilization rate of the uplink data resource and a transmission success rate of the uplink data.