A method for signal transmission in a NR system, comprising: receiving, by a terminal device, first configuration information transmitted by a network device; determining, by the terminal device, a first time domain resource and a first time domain granularity corresponding to the first time domain resource according to the first configuration information; searching, by the terminal device, for a downlink control channel on the first time domain resource by taking the first time domain granularity as a searching period, wherein the first time domain granularity is in units of at least one symbol, or a preset quantity of symbols, or a slot, or a micro-slot, characterized by: if the terminal device does not receive the first configuration information transmitted by the network device, determining, by the terminal device, a third time domain resource and a third time domain granularity corresponding to the third time domain resource according to a predefined third configuration information; and searching, by the terminal device, for the downlink control channel on the third time domain resource by taking the third time domain granularity as a searching period, wherein the third configuration information is determined according to at least one of: a frequency band, a carrier, a system bandwidth, and a numerology. receiving, by a terminal device, first configuration information transmitted by a network device; determining, by the terminal device, a first time domain resource and a first time domain granularity corresponding to the first time domain resource according to the first configuration information; searching, by the terminal device, for a downlink control channel on the first time domain resource by taking the first time domain granularity as a searching period, wherein the first time domain granularity is in units of at least one symbol, or a preset quantity of symbols, or a slot, or a micro-slot, characterized by: if the terminal device does not receive the first configuration information transmitted by the network device, determining, by the terminal device, a third time domain resource and a third time domain granularity corresponding to the third time domain resource according to a predefined third configuration information; and searching, by the terminal device, for the downlink control channel on the third time domain resource by taking the third time domain granularity as a searching period, wherein the third configuration information is determined according to at least one of: a frequency band, a carrier, a system bandwidth, and a numerology. if the terminal device does not receive the first configuration information transmitted by the network device, determining, by the terminal device, a third time domain resource and a third time domain granularity corresponding to the third time domain resource according to a predefined third configuration information; and searching, by the terminal device, for the downlink control channel on the third time domain resource by taking the third time domain granularity as a searching period, wherein the third configuration information is determined according to at least one of: a frequency band, a carrier, a system bandwidth, and a numerology.