A method for transmitting data over periodic resources configured by a network side device, comprising: configuring, by the network side device, a plurality of groups of periodic resources, and generating a list of periodic resources, wherein the list of periodic resources comprises periodicities of respective periodic resources, and mapping relationships between periodic resources, available Transmission Time Interval, TTI, lengths, and channel conditions; and wherein each of the mapping relationships comprises a correspondence between a periodic resource and an available TTI length, or a correspondence between a periodic resource and a channel condition, or a correspondence between a periodic resource and a combination of an available TTI length and a channel condition; transmitting, by the network side device, the list of periodic resources to a terminal, so that at a transmission time occasion corresponding to a periodicity of a periodic resource, the terminal determining the periodic resource according to the mapping relationships, after determining a TTI length to use for data transmission and/or a channel condition to use for data transmission, and transmitting or receiving data over the determined periodic scheduling resource; determining, by the network side device, at a transmission time occasion corresponding to a periodicity of a periodic resource, the periodic resource according to the mapping relationships, after determining a TTI length to use for data transmission and/or a channel condition to use for data transmission; and transmitting or receiving, by the network side device, data over the determined periodic resource. configuring, by the network side device, a plurality of groups of periodic resources, and generating a list of periodic resources, wherein the list of periodic resources comprises periodicities of respective periodic resources, and mapping relationships between periodic resources, available Transmission Time Interval, TTI, lengths, and channel conditions; and wherein each of the mapping relationships comprises a correspondence between a periodic resource and an available TTI length, or a correspondence between a periodic resource and a channel condition, or a correspondence between a periodic resource and a combination of an available TTI length and a channel condition; transmitting, by the network side device, the list of periodic resources to a terminal, so that at a transmission time occasion corresponding to a periodicity of a periodic resource, the terminal determining the periodic resource according to the mapping relationships, after determining a TTI length to use for data transmission and/or a channel condition to use for data transmission, and transmitting or receiving data over the determined periodic scheduling resource; determining, by the network side device, at a transmission time occasion corresponding to a periodicity of a periodic resource, the periodic resource according to the mapping relationships, after determining a TTI length to use for data transmission and/or a channel condition to use for data transmission; and transmitting or receiving, by the network side device, data over the determined periodic resource.