A method for transmitting system information, comprising: receiving, by a base station, a system information request sent by a terminal; and sending, by the base station, system information to the terminal according to the system information request, wherein the system information comprises minimum system information and other system information, and wherein the minimum system information comprises a bitmap field for indicating a system information block existing in the other system information; wherein the terminal is a terminal in an active state and receiving, by the base station, the system information request sent by the terminal comprises: receiving, by the base station, the system information request sent by the terminal in the active state through a radio resource control message; wherein the method further comprises the following after receiving, by the base station, the system information request sent by the terminal in the active state through the radio resource control message: determining, by the base station, a number of terminals that send the system information request; and determining, by the base station, a transmission mode for sending the system information to the terminals according to the number of the terminals, comprising: determining to send the system information to the terminals in a broadcast transmission mode based on a determination that the number of the terminals is greater than a preset threshold; and determining to send the system information to the terminals through a radio resource control dedicated signaling based on a determination that the number of the terminals is not greater than the preset threshold. receiving, by a base station, a system information request sent by a terminal; and sending, by the base station, system information to the terminal according to the system information request, wherein the system information comprises minimum system information and other system information, and wherein the minimum system information comprises a bitmap field for indicating a system information block existing in the other system information; wherein the terminal is a terminal in an active state and receiving, by the base station, the system information request sent by the terminal comprises: receiving, by the base station, the system information request sent by the terminal in the active state through a radio resource control message; wherein the method further comprises the following after receiving, by the base station, the system information request sent by the terminal in the active state through the radio resource control message: receiving, by the base station, the system information request sent by the terminal in the active state through a radio resource control message; wherein the method further comprises the following after receiving, by the base station, the system information request sent by the terminal in the active state through the radio resource control message: determining, by the base station, a number of terminals that send the system information request; and determining, by the base station, a transmission mode for sending the system information to the terminals according to the number of the terminals, comprising: determining to send the system information to the terminals in a broadcast transmission mode based on a determination that the number of the terminals is greater than a preset threshold; and determining to send the system information to the terminals through a radio resource control dedicated signaling based on a determination that the number of the terminals is not greater than the preset threshold. determining to send the system information to the terminals in a broadcast transmission mode based on a determination that the number of the terminals is greater than a preset threshold; and determining to send the system information to the terminals through a radio resource control dedicated signaling based on a determination that the number of the terminals is not greater than the preset threshold.